UC-NRLF 


B    3    75b    SEE 


EI.HALLOCK 


i 


UNIVERSITY   OF   CALIFORNIA   LIBRARY 

THIS  BOOK  IS  DUE  ON  TOE  LAST  DATE 
STAMPED  B^LOW 


JUN  2  6  REC'D 


5m-10,'22 


TRACTOR  ENGINES 


BY 

EDWARD  F.  HALLOCK 


OVER  140  ILLUSTRATIONS 


A  Complete  Course  of    Lessons   on    the  Construction 

and  Economical  Operation  of  the  Tractor 

Engine;  Ajustments  and  Repairs 

Made  Easy;  How  To 

Aquire  Maximum 

Efficiency 


192C 

AMERICAN  AUTOMOBILE  DIGEST 
CINCINNATI 


COPYRIGHT,  1920 
EDWARD  ROSENTHAL 
CINCINNATI,  OHIO 


CONTENTS. 

CHAPTER  I.  PAGE 

Engine   Principles 1 

CHAPTER  II. 
Features  of  Construction 13 

CHAPTER  III. 
Major  Engine  Parts 43 

CHAPTER  IV. 
Valves  and  Valve  Mechanism 83 

'CHAPTER  V. 
About  the  Fuel  System 107 

CHAPTER  VI. 
Lubrication  of  the  Engine 149 

CHAPTER  VII. 
Cooling 176 

CHAPTER  VIII. 
Care  of  the  Cooling  System 187 

CHAPTER  IX. 
Ignition    System 193 

CHAPTER  X. 
Care  of  Ignition  System , 215 

CHAPTER  XI. 
Engine  Troubles 22S 


FOREWORD. 


WITH  the  thought  in  mind  that  a  clear  con- 
ception of  the  principles  involved  in  the 
operation  of  a  piece  of  machinery  helps  consid- 
erably in  the  matter  of  keeping  the  apparatus 
in  proper  running  condition,  this  little  book  on 
tractor  engines  has  been  prepared. 

First  consideration  throughout  each  of  the 
various  chapters  has  been  given  to  a  complete 
exposition  of  the  basic  principles  on  which  the 
matter  treated  with  depends  for  its  functioning; 
with  these  principles  firmly  implanted  in  the 
mind  of  the  reader,  we  have  felt  better  able  to 
make  plain  to  him  the  points  of  divergence  in 
various  constructions,  and  particularly  the  means 
and  the  methods  of  effecting  adjustments  and 
repairs. 

It  will  be  found,  therefore,  that  each  chapter 
is  a  separate  article,  quite  capable  of  standing 
alone  and  dealing  exhaustively  with  the  subject 
matter  in  hand.  This  arrangement,  we  have 
felt,  makes  for  coherence  and  clarity  to  the  end 
that  the  progress  of  the  student  tractor  operator 
or  owner  is  furthered. 

EDWARD  F.  HALLOCK. 

NEW  YORK,  December  7,  1919. 


CHAPTER  I. 

Engine  Principles. 

Basic    Principles    on    Which    Engine    Operation 

Depends;    Necessary    Components    and 

Cycle  of  Operations  of  the 

Practical  Motor. 

BROADLY  speaking,  the  engine  employed 
for  the  operation  of  any  tractor  is  a  "heat 
engine" — a  machine  for  taking  energy  in  the 
form  of  heat  and  converting  it  into  useful  work, 
which  is  just  another  way  of  saying  mechanical 
energy. 

The  effect  which  heat — considering  it  now  as 
a  rise  in  temperature — has  on  a  congregation  of 
people  is  much  the  same  as  it  exerts  on  matter 
in  general.  If,  for  instance,  we  have  a  crowd 
of  folks  huddled  together  under  low  temperature 
conditions,  and  we  suddenly  elevate  the  tempera- 
ture greatly,  the  individual  members  of  the  group 
are  going  to  get  as  far  away  from  each  other 
as  the  degree  of  temperature  demands — in  other 
words,  until  each  one  obtains  a  fair  measure 
of  comfort.  In  so  doing,  it  will  be  appreciated 
that  the  mass  will  spread  out  over  a  greater  area 
— it  will  expand,  in  other  words — the  expansion 
of  the  whole  being  due  to  the  individual  move- 
ment of  the  many  people  who  make  up  the  group. 

We  find  that  matter,  be  it  solid,  liquid  or 
gaseous  as  to  state,  acts  exactly  the  same'  under 
the  effect  of  heat  or  change  in  temperature.  Heat 
a  bar  of  iron,  for  instance,  and  all  the  individual 
molecules  will  exert  themselves,  and  the  result 
will  be  the  expansion  of  the  bar  exhibited  as  an 


2  Tractor  Engines. 

increase  in  length,  width  and  depth — in  other 
words,  an  increase  in  volume. 

Expansion,  of  course,  entails  movement,  and 
movement  is  mechanical  energy.  The  heat  we 
have  put  into  the  bar  of  metal,  therefore,  is  not 
lost;  but  it  is  converted  into  mechanical  energy 
and  the  metal  bar  is,  in  reality,  a  heat  engine. 

If  now  we  take  such  a  bar  and  hold  one  end 
fast  against  all  movement  and  to  the  other  end 
we  attach  a  rod  pivoted  to  the  bar  and  with  its 
other  end  journaled  on  a  crank,  as  shown  by 
Figure  1,  it  will  plainly  be  seen  that  if  we  heat 


FJG.l 


Fig.    1.      Elementary   prin- 
ciple of  heat  engine. 


the  bar  to  such  an  extent  that  it  expands  a  dis- 
tance equal  to  the  throw  or  travel  of  the  crank, 
the  crank  will  be  turned,  imparting  rotary  mo- 
tion to  the  crankshaft.  It,  is  also  conceivable 
that  mounted  on  that  shaft  we  can  have  a  fly- 
wheel or  balance  wheel  which  will  store  up  suf- 
ficient.  energy  to  carry  the  crank  over  the  "dead 
center,"  so  that  when  the  flame  is  removed  and 
the  bar  begins  to  cool  off,  and  thereby  to  con- 
tract again  and  return  to  its  original  size,  it  will 
carry  the  crank  back  once  again,  imparting  rotary 
motion  to  the  shaft.  We  therefore  obtain  con- 


Engine  Principles.  3 

tinuous  rotary  motion  simply  by  applying  the 
flame  at  the  proper  time  and  withdrawing  it 
when  the  outer  end  of  the  stroke  is  reached. 

With  such  a  simple  heat  engine  there  must  be 
encountered  considerable  loss  of  energy.  There 
is  no  means,  for  instance,  of  preventing  direct 
heat  loss  by  radiation;  at  the  same  time  there  is 
an  indirect  loss  due  to  the  fact  that  we  are 
taking  advantage  of  the  longitudinal  expansion 
of  the  metal  only — its  expansion  in  the  other  two 
directions  takes  place  at  the  same  relative  rate 
as  the  elongation  under  the  change  in  tempera- 
ture; but  the  potential  power  from  this  breadth 
and  depth  expansion  which  entails  the  use  of 
heat  to  engender  it,  is  lost  to  us. 

It  is  not  hard  to  appreciate,  therefore,  that 
despite  its  beautiful  simplicity,  such  an  engine 
must  be  very  inefficient.  Other  drawbacks  are 
the  element  of  time,  for  it  needs  a  considerable 
interval  to  raise  the  temperature  of  a  piece  of 
metal,  depending  on  the  material  itself  and  its 
thermal  capacity,  its  weight,  size  and  shape  and 
the  flame  employed,  and  the  length  of  bar  neces- 
sary to  obtain  sufficient  enlargement  under  any 
reasonable  temperature  change  in  order  to  make 
a  practical  machine. 

In  order  to  make  a  practical  heat  engine  which 
will  be  sufficiently  efficient  to  make  its  use  de- 
sirable from  an  economic  standpoint,  the  expand- 
ing medium  we  use  must  be  capable  of  great 
expansion  on  a  comparatively  limited  change  in 
temperature ;  must  be  capable  of  undergoing  this 
expansion  with  the  utmost  rapidity;  and  must 
be  of  such  nature  that  the  forces  obtained  from 
its  expansion  in  all  three  directions  are  capable 
of  being  resolved  into  a  single  force  acting  in 
one  direction  without  mechanical  complication. 

Let  us  consider  for  a  moment  the  action  of 


4  Tractor  Engines. 

gases  under  heat.  We  find  that  if  we  have  a 
vessel  containing  one  quart  of  any  true  gas  at 
atmospheric  pressure  and  0  degrees  Centigrade, 
and  the  vessel  employed  is  gas  tight  and  perfectly 
flexible,  and  we  heat  the  gas  to  1  degree  C,  it 
has  expanded  1/273  of  its  original  volume — in 
other  words  we  now  have  in  the  vessel  1  1/273 
quarts  of  gas.  And  for  each  increase  of  1  de- 
gree C.  the  gas  will  expand  1/273  of  its  volume 
at  0  degrees  C.  If,  then,  we  heat  the  gas  up 
to  273  degrees  C.  we  will  have  added  273/273 
of  a  quart  to  the  vessel — that  is,  we  will  have 
added  .another  quart  of  gas  to  the  original  quart, 
or  will  have  doubled  its  volume. 

We  nave  considered  in  the  above  that  there 
has  been  no  change  in  pressure — it  has  remained 
at  atmospheric  pressure  throughout. 

The  example  given  is  simply  a  concrete  way 
of  expressing  a  well-known  law  of  physics,  known 
as  the  Law  of  Charles.  Given  any  true  gas,  its 
volume  will  increase  by  1/273  of  its  volume  at 
0  degrees  Centigrade  for  every  increase  of  1 
degree  C.,  considering  constant  pressure  through- 
out the  change. 

If  in  the  case  of  the  vessel  given  above,  in- 
stead of  being  flexible  it  was  perfectly  tight  and 
inflexible  so  that  it  could  not  increase  in  capacity, 
and  we  heated  the  air  from  0  degrees  C.,  and 
at  atmospheric  pressure  to  273  degrees  C  we 
would  have,  at  the  latter  temperature,  two  quarts 
of  air  forced  into  a  one-quart  vessel.  Naturally, 
its  pressure  would  be  increased,  and  whereas 
the  pressure  was  approximately  15  pounds  to  the 
square  inch  at  the  lower  temperature  and  smaller 
volume,  it  would  be  approximately  30  pounds  to 
the  square  inch  at  the  increased  temperature. 

In  other  words,  had  we  taken  the  original  quart 
of  gas  and  without  change  of  temperature  com- 


Engine  Principles. 


ASSEMBLY  OF  PISTON,  CONNECTING  ROD.  AND  CRANK 


pressed  it  into  a  half-quart  vessel,  we  would 
have  similarly  doubled  the  pressure.  In  the 
instance  given  above,  however,  by  increasing 
the  temperature  instead  of  holding  it  constant, 
we  doubled  the  quantity  of  gas  contained  in  a 
vessel  without  enlarging  the  vessel;  and  conse- 
quently we  doubled  its  pressure. 

This  concretely  expresses  a  second  law  of 
physics  bearing  on  the  behavior  of  gases,  the 
Law  of  Boyle :  The  pressure  of  a  gas  varies 
inversely  as  its  volume,  considering  constant 
temperature. 

We  find  that  a  gas  will  fulfill  the  conditions 

set  forth  above  for 
an  expansive  me- 
dium for  employ- 
ment in  a  practical 
heat  machine.  Con- 
trasted with  solids 
and  liquids,  its  rate 
of  expansion  per 
degree  of  temper- 
ature rise  is  great; 
at  the  same  time, 
unlikft  the  solid,  it 
can  be  so  confined 
in  a  vessel  that  width  and  breadth  expansion  are 
impossible,  the  expansion  in  these  directions  be- 
ing resolved  into  increased  length  under  the  heat, 
which  is  distinctly  to  our  advantage. 

Our  simplest  engine  using  a  gas  as  the  expand- 
ing medium,  then,  would  take  the  form-  shown 
in  Figure  2.  Here  we  have  a  cylindrical  vessel 
provided  with  a  loose-fitting  plug  made  just  snug 
enough  in  the  smooth  bore  of  the  cylinder  to 
prevent  leakage  of  the  gas  past  the  sides ;  yet 
sufficiently  loose  to  permit  of  free  up  and  down 
movement  of  the  plug  itself,  which  in  the  engine 


Fig.  2.     The  heat  engine  resolved 
into  its  simplest  elements. 


6  Tractor  Engines. 

we  are  pleased  to  call  the  "piston."  Connecting 
the  piston  to  the  crank  on  the  shaft,  whereby  the 
latter  is  set  in  motion,  is  a  rod  called  the  "con- 
necting rod."  The  arrangement  is  such  that 
every  time  the  piston  moves  outward  in  its  cylin- 
der bore,  the  crank  is  turned,  and  every  time  it 
moves  back,  the  crank  'is  carried  back,  giving 
rotary  motion  to  the  shaft.  In  order  to  carry  the 
crank  past  the  dead  center  at  each  end  of  the 
piston  stroke,  a  balance  or  flywheel  is  mounted 
on  the  shaft,  which  stores  up  sufficient  energy 
to  carry  on  the  motion  when  the  crank  has 
reached  its  dead  center. 

Reference  to  the  sketch  will  indicate  that  a 
quantity  of  air  is  trapped  in  the  space  above  the 
piston  in  the  cylinder.  If,  now,  we  apply  a  torch 
or  some  other  source  of  heat  to  the  outside  of 
the  cylinder,  the  trapped  air  within  will  be 
warmed.  Air,  .of  course,  is  a  gas — or  rather  a 
mixture  of  gases — and  it  will  accordingly  follow 
the  laws  for  expansion  of  gases  under  heat  set 
forth  above,  with  the  result  that  pressure  is  cre- 
ated within  the  cylinder  in  exact  accordance  with 
the  increase  in  temperature  of  the  air  within. 
The  increase  vgoes  on  until  such  time  as  the  pres- 
sure on  the  piston  becomes  sufficiently  great  to 
cause  it  to  move  outward,  turning  the  crank  and 
setting  the  engine  in  motion. 

Such,  in  fact,  is  the  principle  on  which  the  hot- 
air  engine  operates.  It  is  a  slow-moving,  low- 
powered,  inefficient  engine;  to. obviate  its  faults, 
speed  of  action,  whereby  considerably  greater 
power  is  obtained  with  the  use  of  the  same 
amount  of  machinery,  is  essential. 

In  the  internal  combustion  engine,  therefore, 
instead  of  applying  our  heat  to  the  outside  of 
the  cylinder  as  a  means  of  elevating  the  temper- 
ature of  the  gases  within,  we  intimately  mix 


Engine  Principles.  7 

the  fuel  we  are  m'mg  with  the  air  which 
is  serving  as  the  expanding  medium,  in  ex- 
actly the  proper  proportions  to  form  a  com- 
bustible mixture.  When  we  ignite  this  mix- 
ture the  burning  of  the  fuel  occurs  almost 
instantaneously;  there  is  a  sudden  rise  and  a 
great  rise  in  temperature  so  that  the  air  ex- 
pands, causing  pressure  on  the  piston  almost 
immediately. 

In  order  to  make  a  practical  internal  combus- 
tion engine,  therefore,  we  must  provide  a  cylinder, 
piston  and  crankshaft  assembly  exactly  as  indi- 
cated above;  but  we  must  also  provide  a  means 
of  getting  a  fuel  charge  into  the  cylinder  at  the 
proper  time  and  mixed  with  the  proper  quantity 
of  air  to  form  an  explosive  mixture.  Also 
we  must  provide  a  means  of  getting  rid  of 
the  burned  gases  after  they  have  fully  ex- 
panded and  performed  their  work  on  top  of  the 
piston. 

We  have,  leading  into  the  cylinder — or  rather 
into  the  combustion  chamber,  which  is  the  space 
in  the  cylinder  above  the  piston  when  the  latter 
is  at  top  stroke,  in  which  chamber  the  actual 
burning  of  the  gases  takes  place — an  intake  pipe 
by  means  of  which  the  mixture  of  gas  (vapor- 
ized gasoline  or  kerosene  in  the  case  of  the  trac- 
tor engine)  and  air  is  introduced  into  the  cham- 
ber at  exactly  the  proper  time.  This  passage  is 
closed  by  means  of  a  little  valve  shaped  like  a 
manhole,  and  provided  with  a  stem  by  means 
of  which  the  valve  can  be  raised  from  its  seat 
and  the  passage  opened  for  the  reception  of  the 
gases  at  the  proper  instant.  This  valve  closes 
tight  against  leakage  of  the  pressure  at  all  other 
times  and  is  normally  held  firmly  to  its  seat  by 
a  strong  spring.  It  is  called  the  "inlet"  valve 
or  "intake"  valve. 


8 


Tractor  Engines. 


Also  provided  is  a  second  passage  closed  by  a 
similar  valve,  which  is  opened  at  the  proper  time 
for  the  expulsion  of  the  burned  gases,  and  kept 
tightly  closed  against  all  leakage  at  all  other 
times.  It  is  called  the  "exhaust"  valve. 

In  diagrams  in  Figure  3,  the  placing  of  these 
valves  and  passages  and  the  action  of  these 
valves  in  effecting  the  inlet  and  exhaust  of  the 
gases  at  exactly  the  proper  time  with  relation 
to  the  piston  stroke  are  indicated.  In  diagram  A, 


FIG.  3 

Fig.  3.     Indicating  the  four  strokes  in  the  cycle  of  operations 
of  the  tractor  engine. 

as  can  be  plainly  seen,  the  piston  is  traveling 
downward,  and  in  doing  so  is  acting  like  the 
plunger  of  a  suction  pump,  creating  a  partial 
vacuum  behind  it.  The  inlet  valve  has  been 
opened,  and  this  suction  created  by  the  piston 
is  relied  upon  to  pull  into  the  cylinder  a  full 
charge  of  mixture  of  proper  proportions  for 
firing  from  a  mixing  valve  or  a  carburetor,  as 
the  case  may  be. 


Engine  Principles.  9 

When  the  piston  reaches  bottom  stroke  so 
that  no  more  charge  can  be  drawn  into  the  cylin- 
der, the  inlet  valve  is  closed  and  the  cylinder 
becomes  a  closed  chamber.  As  the  piston  comes 
up,  carried  on  by  the  energy  stored  up  in  the 
revolving  flywheel,  the  charge  is  compressed. 
Just  about  the  time  when  the  piston  reaches  its 
top  center  and  the  compression  is  greatest,  as 
shown  in  diagram  C,  an  electric  spark  is  caused 
to  jump  the  gap  of  the  spark  plug,  and  from  this 
spark  the  mixture  takes  fire,  burns,  expands, 
creates  pressure  within  the  cylinder  which  drives 
the  piston  down,  imparts  energy  to  the.  crank- 
shaft arid  to  the  flywheel;  whereby  power  is 
obtained. 

It  will  be  seen  that  on  the  compression  stroke 
of  the  piston  and  on  the  power  stroke,  both  in- 
take and  exhaust  valves  have  been  kept  tightly 
closed ;  this,  of  course,  is  to  prevent  the  escape 
of  the  fuel  charge  on  the  compression  stroke  and 
of  the  forces  of  combustion  on  the  power  stroke ; 
such  loss  would  mean  reduced  pressure  on  the 
piston  and  loss  of  power. 

On  the  next  upstroke  of  the  piston,  as  shown 
in  diagram  D,  the  exhaust  valve  is  opened;  and 
since  on  the  power  stroke  all  the  energy  has  been 
taken  from  the  expanding  gases,  they  are  blown 
out  by  the  ascending  piston  through  the  exhaust 
valve,  thereby  clearing  the  cylinder  for  the  re- 
ception of  a  charge  of  fresh  mixture.  Imme- 
diately the  piston  reaches  its  top  center  after 
expulsion  of  the  gases,  the  inlet  valve  is  opened 
again  and  the  cycle  of  operations  is  repeated, 
whereby  continuous  action  is  obtained. 

It  will  be  seen  that  in  the  accomplishment  of 
one  complete  cycle,  the  piston  has  made  four 
complete  strokes  lengthwise  of  the  cylinder.  It 
went  down  once  on  the  inlet  or  suction  stroke; 


10  Tractor  Engines. 

up  once  on  the  compression  stroke;  down  again 
on  the  power  stroke,  and  up  once  again  on  the 
exhaust  stroke.  From  the  fact  that  four  such 
piston  strokes  are  necessary,  an  engine  operating 
on  this  principle  is  called  a  "four-stroke-cycle" 
engine,  or  in  more  common  parlance,  a  four- 
stroke  engine.  There  are  internal  combustion 
engines  which  operate  on  other  cycles;  there  is 
one,  for  instance,  which  accomplishes  its  entire 
function  in  two  strokes  of  the  piston.  But  for 
tractor  service  engines  operating  on  any  but  the 
four-stroke-cycle  have  made  no  progress,  how- 
ever serviceable  they  may  be  in  other  fields, 
so  that  a  description  of  their  operation  in  a  book 
dealing  strictly  with  modern  tractor  engine  prac- 
tice will  serve  no  useful  purpose. 

The  reader,  in  going  over  the  diagrams  pictur- 
ing the  cycle  of  operations,  will  also  notice  that 
in  going  through  one  complete  cycle  the  crank- 
shaft made  two  complete  revolutions.  There  is, 
then,  one  power  stroke  to  each  four  piston  strokes 
with  a  single  cylinder  engine  of  this  type,  and 
the  flywheel  must  be  so  proportioned  as  to  carry 
the  piston  through  three  idle  strokes  after  each 
power  stroke  before  the  piston  is  again  in  posi- 
tion to  impart  power  to  the  engine  crankshaft. 

If  we  were  to  actuate  the  valves  directly  from 
the  crankshaft,  it  must  be  evident  that  each  valve 
would  open  once  for  each  revolution  of  the 
crankshaft.  As  a  matter  of  fact,  as  we  can 
prove  for  ourselves  by  referring  once  again  to 
the  diagrams,  the  inLet  valve  opens  only  once 
for  each  two  revolutions  of  the  crankshaft,  and 
the  exhaust  valve  has  a  similar  movement.  The 
exhaust  valve  is  open  for  one-half  of  one  revo- 
lution, the  inlet  valve  for  the  second  half  of 
the  same  revolution,  while  for  the  second  revo- 
lution both  are  shut  tight. 


Engine  Principles. 


11 


It  would  not  do,  obviously,  to  open  them  di- 
rectly from  the  crankshaft;  we  must  interpose 
a  second  shaft  timed  to  rotate  at  half  the  speed 
of  the  crankshaft  in 
order  to  obtain  the 
proper  motion  of  our 
valves  relative  to  the 
piston  travel.  The  ar- 
rangement of  this  shaft, 
which  we  call  the  "cam- 
shaft," is  in- 
dicated  in 
Figure  4.  It 
will  be  seen 
that  a  gear 
wheel  is 
mounted  on 
the  crank- 
shaft,  engag- 
ing with  a  second  gear  of  twice  the  diameter 
of  th£  crankshaft  gear  mounted  on  the  camshaft, 
the  relative  sizes  being  such  that  the  camshaft 
rotates  at  half  crankshaft  speed. 


FIC.4 


Fig.    4.     Showing   how  the  camshaft 
is  driven  at  half  crankshaft  speed. 


Fig.  5.     Action  of  cam  in  opening  the  valve. 

On  the  camshaft  is  mounted  an  irregularly- 
shaped  wheel — a  wheel  with  a  hill  on  it  and 
called  a  cam — for  each  valve.  Every  time  the 


12  Tractor  Engines. 

hill  on  the  cam  comes  around,  it  raises  the  valve 
push-rod  (see  Figure  5),  which  in  turn  pushes 
up  against  the  bottom  of  the  valve  stem  and  ele- 
vates the  valve  against  the  action  of  the  valve 
spring.  When  the  hill  passes,  the  valve  spring 
returns  the  valve  to  its  seat.  Where  the  valves 
are  of  the  overhead  or  "valve-in-head"  type,  the 
push-rod  is  longer  and  transmits  its  motion  to  a 
rocker  arm  or  lever  which  bears  down  against  the 
valve  stem,  opening  the  valve  at  the  proper  time. 
Naturally,  the  hill  on  the  cam  is  exactly  pro- 
portioned to  start  opening  the  valve  at  the  proper 
time  and  to  hold  it  open  just  long  enough;  and 
the  cams  are  so  set  on  the  camshaft  as  to  time 
their  performance  correctly  with  the  piston  travel. 


CHAPTER  II. 

Features  of  Construction. 

Wkerein    Multi-Cylindered    Engines    Excel    for 

Tractor  AVork  and  tKe  Standard 

Types  Offered. 

IN  the  preceding  chapter  we  have  gained  an 
insight  into  the  basic  principles  upon  which 
the  tractor  engine  operates.  In  the  employment 
of  these  basic  principles,  all  tractor  engines  are 
identical — in  their  details  of  construction,  how- 
ever, they  differ  radically  from  one  another.  It 
is  the  purpose  of  the  second  chapter  to  go  fully 
into  modern  tractor  engine  construction,  indicat- 
ing the  functions  of  the  various  parts  and  indi- 
cating clearly  wherein  one  engine  differs  from 
the  next  and  the  reasons  therefor. 

We  have  had  under  consideration  so  far  only 
such  engines  as  employ  a  single  cylinder.  It 
must  be  evident  that  on  a  vehicle  like  a  tractor, 
where  smooth  progress  is  desirable,  the  produc- 
tion of  power  in  "jerks"  such  as  we  have  seen 
results  from  the  single-cylinder  construction,  is 
by  no  means  ideal.  It  would  be  far  better,  for 
instance,  if  instead  of  obtaining  only  one  power 
stroke  for  each  two  revolutions  of  the  crank- 
shaft, we  could  obtain  two  power  strokes;  still 
better  if  we  were  able  to  get  four  power  strokes, 
or  one  for  each  half  revolution  of  the  crankshaft. 
That  means  that  we  would  obtain  one  power 
stroke  for  every  180  degrees  of  crankshaft 
movement. 

It  is  quite  impossible,  of  course,  to  obtain 
such  desirable  results  from  a  single-cylinder  .en- 
ds) 


14  Tractor  Engines. 

gine  performing  on  the  four-stroke  cycle.  It  is 
quite  possible,  however,  to  arrange  two  such 
cylinders,  or  four  such  cylinders,  to  impart  im- 
pulses to  a  single  crankshaft ;  and  by  properly 
arranging  the  crankthrows,  and  the  cams,  to 
cause  these  cylinders  to  deliver  their  power  to 
the  crankshaft  at  different  times. 

Such  is  the  trend  of  modern  tractor  engine 
practice ;  single-cylinder  engines  which  once  were 
almost  universally  used  for  tractor  work  are 
fast  becoming  obsolete ;  the'  two-cylinder  engine 
still  persists  on  several  well-known  makes  of 
tractors,  but  even  it  is  giving  way  at  the  present 
time  to  the  four  and  six-cylinder  types  which 
have  made  such  great  headway  in  the  automobile 
field  and  which  are  fast  becoming  standard'  in 
the  tractor  industry. 

The  four-cylinder  engine  is  by  far  the  most 
popular  at  the  present  writing,  there  being  very 
few  engines  of  a  greater  number  of  cylinders  ; 
and  since  the  flexibility  which  we  demand  in  the 
passenger  automobile  is  by  no  means  essential  to 
tractor  service,  it  seems  altogether  likely  that 
four  cylinders  will  be  the  accepted  standard  of 
the  future  tractor  engine.  It  is  worthy  of  note 
that  in  only  a  single  instance  has  a  greater  num- 
ber of  cylinders  than  six  been  adopted — that  is, 
in  the  case  of  the  Common  Sense  tractor  pro- 
duced on  the  Pacific  Coast  and  which  employs 
a  Herschell-Spillman  engine  with  eight  cylinders. 

Indicative  of  the  fact  that  for  all  the  progress 
made  toward  the  multi-cylinder  engine,  the 
single-cylinder  type  is  not  as  yet  a  dead  issue, 
nor  its  production  confined  to  the  smallest  manu- 
facturers, are  the  accompanying  photographs  of 
typical  engines  of  that  type  produced  by  two  of 
the  largest  tractor  builders  in  the  country. 


Features  of  Construction. 


15 


Fig.  6.     Single-cylinder  horizontal  engine 
on  18-35  Rumely. 


Figure  6  rep- 
resents the 
single  -  cylin- 
der horizon- 
tal engine 
employed  on 
the  model 
18-35  tractor 
produced  by 
the  Advance- 
RumelyTrac- 
tor  Co.,  La 
Porte,  Ind., 
which  has 
given  a  re- 
markable account  of  itself  over  past  years,  while 
Figure  7  pictures  a  somewhat  similar  type  of 
engine,  which  is  used  on  the  10-20  Mogul  trac- 
tor produced  by  the  International  Harvester 
Corporation. 

It  will  be  noted  in  the  case  of  the  latter  that 
the  valves  are  placed  in  the  cylinder  head,  and 
that. the  engine  is  "hopper"  cooled.  A  modified 
"T"-head  cylinder  arrangement  prevails  in  the 
case  of  the  Rumely  engine. 

Not  always, 
in  the  case  of 
the  single-cyl- 
inder engine, 
is  the  horizon- 
tal cylinder  ar- 
rangement ad- 
hered to.  Take, 
for  instance, 
the  B  e  e  m  an 
garden  t  r  a  c- 
tor,  which  is  a 
small  hand-  eng*. 7'  Mogul  10'20  single ' cylinder 


16 


Tractor  Engines. 


operated  machine,  and  a  vertical  cylinder  engine 
of  this  type  is  employed. 

Two-cylinder  tractor  engines,  which  still  are 
commonly  met  with  throughout  the  industry, 
come  in  three  different  forms  as  to  the  arrange- 
ment of  the  cylinders.  The  most  commonly  met 
with  is  the  "opposed"  cylinder  type,  with  two 
horizontal  cylinders  facing  each  other  on  a  sin- 
gle crankcase.  Such  an  engine  is  pictured  in  dia- 
grammatic form  in  Figure  8,  with  the  various 


CAM  GEARS- 
CARBON  STEEL 
ACCURATELY 
CUT  TEETH 


BRONZE  BACK 

NICK  if  BABBIT  LINED 

BEARINGS 

lAsnv  ADJUSTED 


flG.8 


Fig.  8.     Two-cylinder  opposed  engine  of  the  Bull  Tractor. 

parts  indicated  for  the.  convenience  of  the  reader. 
The  engine  in  the  figure  is  the  one  employed  on 
the  Bull  tractor,  a  three-wheeled  type  which  is 
held  in  great  respect. 

The  real  virtue  of  a  two-cylinder  engine  of 
this  type  is  the  close  approach  to  perfect  balance 
which  the  arrangement  of  the  various  parts  per- 
mits. It  will  be  appreciated  that  with  the  single- 
cylinder  engine  the  sudden  stopping  and  starting 


Features  of  Construction.  17 

of  the  piston  at  each  end  of  its  stroke  entails 
considerable  vibration,  which  is  registered  on  the 
entire  tractor  mechanism.  With  a  view  of  elim- 
inating this  fault  to  the  greatest  possible  degree, 
makers  of  this  type  of  engine  attach  counter- 
weights to  the  crankshaft  at  points  opposite  the 
crankpin  in  order  to  balance  the  weight  of  the 
reciprocating  members — the  piston  and  connect- 
ing rod  assembly.  This  arrangement  is  clearly 
indicated  in  Figure  9,  which  shows  a  crankshaft 
and  piston  assembly  from  an  engine  of  this  type. 


Fig.  9.     Counterbalanced  single-cylinder  crankshaft  (Mogul  10-20). 

In  practice,  however,  it  has  been  found  im- 
possible to  achieve  perfect  balance  of  the  recip- 
rocating members  by  means  of  rotating  counter- 
weights, and  while  the  latter  do  a  measure  of 
good,  the  results  obtained  are  by  no  means  per- 
fect. If,  however,  we  apply  to  the  crankshaft, 
exactly  opposite  the  crank,  a  reciprocating  mass 
exactly  equal  and  similar  to  the  piston  and  con-  r\ 
necting  rod,  the  vibrations  set  up  by  this  balanc- 
ing mass  will  exactly  counterbalance  those 
engendered  by  the  piston  movement,  and  smooth 
operation  of  the  engine  will  be  promoted. 

As  can  be  seen  by  the  illustration  (Figure  8) 


18 


Tractor  Engines. 


in  the  two-cylinder  opposed  engine,  the  piston 
and  connecting  rod  of  the  second  cylinder  are  so 
arranged  as  to  take  the  place  of  this  counter- 
balancing mass,  the  crankthrows  being  set  at 
180  degrees  apart.  Hence,  the  vibratory  forces 


Top  view  of  12-25 
H.  «-.  motor.  The 
8-16  H.  P.  motor  is 
also  built  in  this  style. 


Cam   case  on   12-25 
H.   P.  motor. 


Cam  case  on  25-50 
H.  P.  motor. 


K 

Si  maim 


Top  view  of  25-50  H.  P.  motor.  The  18-36  and  40-80  H.  P. 
motors  are  also  built  in  this  style.  Note  how  narrow  this  four- 
cylinder  motor  is  and  how  strong  in  construction. 

Fig.  10.  .  Some  views  which  emphasize  the  features  of  A  very 
engines. 


Features  of  Construction.  19 

set  up  by  one  piston  occur  at  exactly  the  same 
time,  are  equal  to  and  in  the  opposite  direction 
from  those. established  by  the  other  one,  so  that 
they  neutralize  each  other,  a"nd  perfectly  smooth 
operation  is  the  result.  It  can  plainly  be  seen 
that  the  use  of  counterbalances  on  the  crankshaft 
of  such  an  engine  is  needless. 

In  Figure  10  are  shown  similar  views  of  the 
Avery  tractor  engine  of  the  opposed  type  in 
both  two-cylinder  and  four-cylinder  types.  The 
main  points  of  divergence  between  the  Bull  and 
Avery  two-cylinder  engines  are  the  employment 
of  L-head  cylinders  with  direct  acting  thrust 
valves  on  the  former,  as  against  the  I-head 
cylinder  with  valves  in  the  head  by  the  latter ; 
also  in  the  Avery  a  single  camshaft  is  employed 
to  time  the  action  of  all  four  valves,  while  in  the 
Bull  engine  the  employment  of  two  camshafts  is 
indicated. 

In  connection  with  the  Avery  tractor  it  may 
be  said  that  this  manufacturer  has  adhered  to 
the  opposed  type  of  engine*  for  many  years  and 
developed  that  type  to  a  point  of  refinement  that 
is  hard  to  improve  upon.  In  the  four-cylinder 
Avery  job  still  another  source  of  vibration  is 
eliminated.  It  will  be  noticed  that  in  the  two- 
cylinder  engine  the  cylinders  are  "staggered" 
slightly,  due  to  the  arrangement  of  the  throws 
on  the  crankshaft.  Because  of  this  staggering  it 
is  evident  that  the  pull  of  one  rod  on  the  crank- 
shaft, due  to  the  piston  stoppage,  is  delivered  at 
a  different  place  from  the  pull  of  the  other  rod 
and  is  opposite  in  direction.  This  will  cause  the 
crankshaft  to  act  somewhat  like  a  lever,  in- 
fluencing it  to  rotate  in  a  longitudinal  plane  about 
a  center  midway  between  the  points  of  attach- 
ment of  the  two  rods  to  the  shaft.  Since  there 
is  a  reversal  of  movement  of  the  pistons  twice 


20 


Tractor  Engines. 


for  each  revolution  of  the  shaft,  and  since  such 
reversal  will  cause  a  tendency  for  the  longi- 
tudinal rotation  of  the  shaft  to  reverse  also,  we 
have  a  source  of  an  annoying  vibration  which 
is  very  evident  at  high  engine  speeds. 

If,  now,  we  note  the  arrangement  of  the 
crankthrows  on  the  four-cylinder  engine,  we 
find  that  those  on  the  two  outside  cylinders  are 
on  the  same  plane,  while  those  on  the  two  inside 
cylinders  are  180  degrees  away,  both  rods,  in 
fact,  attaching  to  the  same  pin.  If  we  con- 
sider the-  action  of  the  two  outside  pistons 

at  t  h  e  mo- 
ment of  re- 
ve  r  s  al,  we 
find  that  both 
are  acting  in 
the  same  di- 
r  e  c  t  i  o  n,  so 
that  if  the 
shaft  were 
fulcrumed  on 
a  center  the 
resulting 
forces  would 
counterbalance  each  other  and  would  not  tend  to 
cause  rotation  of  the  shaft  in  a  longitudinal  plane 
as  with  the  two-cylinder  engine.  Likewise,  the 
forces  which  would  tend  to  cause  such  rotation 
from  the .  inside  cylinders  are  exactly  counter- 
balanced. At  the  same  time,  the  two  pistons  on 
one  cylinder  block  exactly  balance  those  on  the 
other  block,  so  that  all  reciprocating  forces  are 
balanced,  and  an  engine  which  is  perfectly  bal- 
anced under  all  conditions  results. 

In  Figure  11  is  shown  a  photograph  of  still  an- 
other opposed  two-cylinder  engine,  which  is 
fitted  to  the  Ingeco  tractor.  It  also  is  of  the 


Fig.    11. 

type. 


Ingeco   engine   of  the  opposed 


Features  of  Construction.          21 

overhead  valve  type  and  its  chief  claim  to 
novelty  is  in  the  fitting  of  two  carburetors, 
whereby  the  necessity  for  a  long  intake  mani- 
fold entailing  condensation  under  cold  weather 
conditions  is  done  away  with.  Figure  12  gives 
a  side  view  of  the  two-cylinder  Avery  engine 
making  plain  the  use  of  long  manifolds.  In  the 
illustration  a  double-bowl  carburetor  is  shown, 
one  bowl  serving  for  gasoline  and  the  other  for 
kerosene;  the  shift  from  the  lighter  to  the 


Fig.  12.     Side  view  of  the  Avery  double-cylinder  type. 

heavier  fuel  is  made  when  the  engine  has  become 
sufficiently  warmed  up  to  handle  the  kerosene 
properly. 

It  cannot  be  denied  that  the  double-cylinder 
horizontal  engine  has  certain  advantages  in  the 
way  of  compactness  over  the  opposed  type,  and 
these  advantages  have  led  to  its  adoption  in 
preference  to  the  opposed  engine  by  several 
tractor  manufacturers.  These  advantages  are 


22  Tractor  Engines. 

mainly  a  greater  facility  with  which  the  various 
fuel,  water,  oil  and  exhaust  connections  can  be 
made  and  the  fact  that  such  a  cylinder  arrange- 
ment permits  of  the  two  cylinders  being  cast  to- 
gether in  a  single  block,  making  for  rigidity  and 
lessened  cost  of  production. 

Such  an  engine  is  the  Titan  10-20,  used  on 
one  of  the  International  Harvester  models.  It  is 
pictured  in  Figure  13  and  like  the  Avery,  is  of 


Fig.  13.     Engine  of  Titan  10-20. 

the  overhead  valve  type.  The  chief  drawback  to 
such  an  engine  is  the  inability  to  obtain  perfect 
balance,  or  even  a  close  approach  to  perfect 
balance,  if  the  firing  intervals  are  made  equal. 
In  order  to  bring  about  the  latter  condition,  for 
instance,  on  a  two-cylinder  engine,  it  is  evident 
that  we  will  want  one  power  impulse  for  each 
crankshaft  revolution,  or  360  degrees  of  crank- 
shaft movement.  That  means  that  both  pistons 
must  be  attached  to  the  same  pin  or  to  pins  on 
the  same  plane,  so  that  they  will  travel  together, 


Features  of  Construction.          23 


for  if  they  were  mounted  180  degrees  apart,  as 
in  the  case  of  the  two-cylinder  opposed  type,  it 
is  evident  that  rotating  the  shaft  360  degrees 
after  the  first  cylinder  has  fired  will  result  in  the 
second  piston  being  at  the  bottom  of  its  stroke 
and  in  no  position  to  fire.  The  only  way  to 
have  it  in  position  to  fire  360  degrees  after  the 
first  cylinder  is  to  mount  it  on  the  same  pin,  and 
this  is  the  practice  usually  followed. 

This  practice,  however,  gives  us  two  recipro- 
cating masses 
working 
in  unison  and 
not  opposing 
each  other, 
and  it  is  evi- 
d  e  n  t,  there- 
fore, that  the 
vibration  en- 
tailed will  be 
twice  as  great 
as  in  the  case 
of  a  single- 
cylinder  e  n  - 
gine  with  the 
same  recipro- 
cating masses 
and  turning 
up  at  the 
same  speed.  The  means  taken  to  offset  this  con- 
dition, of  course,  are  the  attachment  of  counter- 
balance weights  to  the  crankshaft,  as  shown  by 
Figure  14,  which  illustrates  a  Rumely  engine  of 
this  type.  The  inability  to  obtain  perfect  bal- 
ance by  this  method  has  been  made  clear  before ; 
it  is  evident  that  such  an  engine,  due  to  its 
tendency  to  vibrate  badly,  is  suitable  for  low 
rotative  speeds  only. 


Fig.  14.  A  Rumely  two-cylinder  hori- 
zontal type  where  balance  has  been  sacri- 
ficed to  obtain  even  firing  intervals. 


24 


Tractor  Engines. 


FIG. IS 


Fig.  15.     Crank-case  with  cover  removed 
from  Rumely  14-28  engine. 


In  the  Rumely  14-28  engine  the  other  alter- 
native has  been  taken  and  even  firing  intervals 

have  been 
sacrificed  i  n 
order  to  at- 
tain an  en- 
gine of  better 
balance.  I  n 
this  case 
the  crank- 
throws  are 
set  180  de- 
grees apart 
so  that  one 
cylinder  fires 
180  degrees 
after  the  other,  and  then  there  is  a  complete 
crankshaft  revolution  with  no  power  impulse. 
With  this  arrangement,  which  is  shown  in  Figure 
15,  it  is  evident  that  the  reciprocating  mass  of 
one  piston  al- 
most exactly 
counter- 
balances  the 
other ;  there 
is  a  slight 
difference  at 
certain  points 
in  the  stroke 
due  to  the 
difference  i  n 
rate  of  accel- 
eration and 
d  e  c  e  1  e  r  a- 
tion  which 
results  from 
the  angularity 
of  the  con- 


Fig.   16. 
motor. 


Top  view  of  the   14-28   Rumely 


Features  of  Construction.  25 

necting  rods ;  however,  balance  in  the  line  of  the 
cylinder  axii  is  almost  perfect. 

It  will  be  seen,  however,  that  whereas  with  the 
opposed  type  of  engine  it  was  simply  necessary 
to  stagger  the  cylinders  slightly  to  give  clearance, 
the  side  by  side  arrangement  of  the  cylinders  in 
this  case  makes  the  points  of  attachment  of  the 
two  rods  quite  far  apart — much  further  than  in 
the  case  of  the  opposed  type.  Considering  lon- 
gitudinal balance  with  relation  to  the  crankshaft, 
therefore,  the  engine  is  greatly  at  a  disad- 
vantage. This  fact  has  been  offset  in  the  engine 
under  consideration  by  the  attachment  of  coun- 
terweights on  opposite  ends  of  the  crankshaft 
and  180  degrees  apart.  The  vibrations  created 
by  these  counterbalances  tend  to  offset  those 
created  by  the  piston  movement  and  give  a 
smooth-running  motor. 

While  the  irregular  firing  of  this  engine  is  by 
no  means  the  ideal  condition,  in  practice  it  has 
not  been  found  to  work  out  greatly  to  the  disad- 
vantage of  the  unit  as  a  whole.  That  this  is 
so  is  attributable  to  the  fact  that  the  flywheel 
used  is  sufficiently  heavy  to  carry  the  engine 
shaft  over  at  substantially  constant  speed,  storing 
up  the  energy  from  the  two  power  strokes  on  the 
first  revolution  and  giving  it  back  to  the  shaft  on 
the  second  revolution  when  there  is  no  power 
stroke.  The  two  cylinders  fire,  of  course,  180  y 
degrees  apart,  there  being  a  lapse  of  360  degrees  ' 
after  the  second  one  fires  before  the  first  one 
fires  again. 

The  peculiarities  of  tractor  design  and  the 
total  lack  of  standardization  prevailing  through- 
out the  industry  have  given  rise  to  many  con- 
structions which  either  never  were  common 
with  the  automobile  engine,  or  at  least  never  sur- 
vived the  experimental  stage.  One  of  these  is 


26  Tractor  Engines. 

the  four-cylinder  engine,  with  the  cylinders  all 
in  a  line  and  placed  horizontally  instead  of 
vertically. 

The  virtue  of  an  engine  of  this  type  is,  of 
course,  the  fact  that  it  lends  itself  readily  to 
proper  placement  in  the  frame  of  the  tractor 
without  bringing  any  of  the  machine  too  high; 
at  the  same  time  it  makes  an  engine  which  is 
very  accessible,  since  not  only  the  valve  mechan- 
ism, which  is  generally  exposed  and  located  on 
top  of  the  cylinders,  but  also  the  bearings  can 


Fig.  17.  Four-cylinder  horizontal  engine  of  Aultman-Taylor 
30-60  model. 

be  reached  in  a  jiffy  when  it  comes  time  to  effect 
adjustments  or  repairs. 

That  this  is  so  is  made  evident  by  Figure  17, 
in  which  is  illustrated  the  engine  of  the  Aultman- 
Taylor  30-60  tractor.  The  facility  with  which 
any  part  of  the  valve  mechanism  can  be  reached 
— as  will  be  seen,  the  valve-in-head  arrange- 
ment is  adhered  to — the  ease  with  which  the 
cylinder  heads  can  be  removed  from  the  two 
cylinder  blocks  and,  the  otherwise  generally  ac- 
cessible location  of  the  engine  parts  and  acces- 
sories are  plainly  obvious. 


Features  of  Construction.          27 


Figure  18,  on  the  other  hand,  gives  a  very 
fair  indication  of  the  facility  with  which  every 
bearing  in  the  engine  can  be  reached,  giving  am- 
ple room  for  relining,  taking  up  on  slack  bear- 
ings or  withdrawing  the  entire  piston  and  con- 
necting rod  assembly  when  it  is  necessary  to  refit 
piston  rings,  renew  the  pistons  or  otherwise  cor- 
rect faults  or  improve  the  operation  of  the 
engine.  The  base  or  crankcase  casting  of  the 
engine  is  split  diagonally,  as  shown,  and  simply 


FI6.I8 


Fig.   18.     Showing  the  accessibility  of  the  internal  mechanism 
of  Aultman-Taylor  30-60  engine. 

undoing  the  cap  screws  with  which  it  is  fastened 
in  place  discloses  the  entire  inner  working 
mechanism  of  the  engine,  and  it  all  can  be 
reached  from  above;  it  is  not  even  necessary  to 
drain  the  crankcase  of  the  oil,  as  would  be  neces- 
sary with  the  vertical  cylinder  engine. 

The  crankshaft  employed  is  of  the  three- 
bearing  type  which  is  commonly  met  with  on 
four-cylinder  engines,  both  horizontal  and  ver- 
tical cylinder  types ;  and  it  will  be  seen  that  the 


28  Tractor  Engines. 

• 

two  outside  crankthrows  are  on  a  plane,  and  the 
two  inside  on  a  plane  180  degrees  away.  The 
effect  is  -that  we  have  perfectly  even  firing  in-j 
tervals,  one  cylinder  firing  at  each  half  revolu- 
tion of  the  crankshaft,  or  at  each  180  degrees ; 
while  at  the  same  time  we  have  a  very  close 
approximation  of  perfect  balance.  It  will  be 
seen,  for  instance,  that  the  reciprocating  masses 
of  the  two  inner  cylinders  are  opposed  to  the 
reciprocating  masses  of  the  two  outer  cylinders, 
so  that  except  for  a  slight  difference  in  piston 
velocities  at  certain  crank  positions,  due  to  the 
angularity  of  the  connecting  rods,  both  weights 
and  velocities  are  equal  on  the  two  sets,  but  the 
direction  of  movement  of  one  set  is  opposite  that 
of  the  other,  so  that  balance  is  obtained.  Con- 
sidering longitudinal  balance,  the  effect  of  the 
two  front-cylinder  reciprocating  masses  is  exactly 
counteracted  by  that  of  the  two  rear  .ones,  so 
that  vibration  from  this  score  is  done  away  with. 

As  tractor  design  progresses  toward  some  ac- 
cepted standard — and  such  progress  has  been 
marked  over  the  past  three  years — the  vertical 
cylinder  type  of  four-cylinder  engine,  following 
closely  automobile  practice,  comes  more  and 
more  into  its  own.  In  fact,  even  the  six-cylinder 
vertical  cylinder  type  is  making  some  progress. 

Doubtless  there  will  always  be  quite  some  dif- 
ference between  the  tractor  engine  and  the  ac- 
cepted automobile  standard ;  difference  which  re- 
sults from  their  different  fields  of .  employment 
and  the  widely  divergent  duties  they  are  called 
upon  to  perform.  Chief  among  these  differences 
will  be  the  weight,  since  it  can  easily  be  believed 
that  the  tractor  engine  will,  for  at  least  some  time 
to  come,  represent  a  heavier  construction  for 
equal  power  output  than  the  automobile  type — 
this  difference  being  due  to  the  fact  that  the  trac- 


Features  of  Construction.          29 

tor  engine  operates  normally  at  three-quarters 
load  constantly  throughout  the  day — it  is  essen- 
tially a  constant-duty  engine  and,  as  such,  prob- 
ably always  will  be  of  the  moderate  speed  type 
and  rather  rugged  in  construction. 

The  automobile  engine,  on  the  other  hand,  is 
called  upon  to  deliver  power  at  only  one-quarter 
its  rated  capacity  throughout  the  greater  part  of 
the  day;  but  for  brief  intervals  it  may  be  taxed 
to  its  limit  or  to  any  extent  between  maximum 
and  minimum  power  development  possibilities. 
It  is  essentially  a  variable  load  engine,  and  since 
the  vehicle  it  is  used  in  connection  with  must  be 
capable  of  high  speed  and  rapid  acceleration, 
light  weight,  in  conjunction  with  great  power,  is 
a  prime  essential.  Quite  as  a  matter  of  course, 
the  automobile  designer  has  gone  to  high  rota- 
tive speeds  in  order  to  satisfy  these  conditions. 

Flexibility  and  quick  pick-up,  on  the  other 
hand,  are  not  required  of  the  farm  tractor — what 
is  wanted  is  a  slow,  steady  pull  with  great  dura- 
bility. Hence  we  can  logically  expect  that  power 
for  power,  the  tractor  engine  will  be  weightier 
and  slower-moving  than  the  automobile  engine. 

There  are  but  a  handful  of  tractor  engines 
which  violate  this  condition.  First  and  foremost 
comes  the  Moline  Universal,  which  employs  a 
four-cylinder  engine  of  the  high-speed  type 
which  is  comparatively  light  in  weight,  but  withal 
very  rugged  in  construction.  Second  is  the  Ford- 
son,  also  employing  an  engine  which  turns  over 
at  a  speed  comparable  with  the  average  automo- 
bile engine.  But  perhaps  the  most  noticeable 
exception  to  the  rule  is  the  Common  Sense  trac- 
tor, which  is  a  Coast  production  and  which  em- 
ploys an  eight-cylinder  V-type  engine,  following 
exactly  automobile  engine  practice. 

That   ruggedness   and   heavy   weight   are   the 


30 


Tractor  Engines. 


rule,  however,  is  made  plain  in  some  of  the  ver- 
tical cylinder  engines  pictured  herewith.  Figure 
19,  for  instance,  illustrates  the  four-cylinder  ver- 
tical engine  employed  on  the  Emerson-Branting- 
ham  (Reeves)  tractor,  rated  at  40  horse-power, 
for  belt  work.  Indicative  of  ruggedness  is  the 
five-bearing  crankshaft,  a  construction  which  has 
all  but  disappeared  from  automobile  practice, 
and  the  employment  of  separately-cast  cylinders. 
The  value  of  the  latter  construction  on  tractor 
work  is  not  to  be  minimized.  The  tractor  engine 

operates  un- 
der totally 
different  con- 
ditions from 
the  automo- 
bile engine 
and  the  fact 
that  its  work 
is  of  the 
hardest,  and 
long  c  o  n  - 
tinued ;  t  h  a  t 
its  temper- 
atures run 
high  and  lub- 
ri  cat  ion  is 

therefore  difficult;  and  that  sufficient  attention 
is,  unfortunately,  not  always  paid  to  the  necessity 
of  keeping  the  air  washer  in  prime  condition,  so 
that  no  grit  will  get  into  the  cylinders,  results  in 
more  frequent  scoring  of  one  or  more  cylinders, 
necessitating  either  replacement  or  reboring. 
With  the  individually-cast  cylinders  the  correc- 
tion can  be  made  at  greatly  reduced  cost,  and  in 
much  less  time  than  when  the  cylinders  are  cast 
in  a  single  block,  necessitating  the  removal  or  re- 


40-65 


.   19.     Cross  section  of  E-B    (Reeves) 
kerosene  motor. 


Features  of  Construction.  31 

placement  of  the  entire  block  in  accordance  with 
the  amount  of  damage  done. 

This  construction  quite  naturally  gives  a  par- 
ticularly long  engine; -much  longer  than  an  en- 
gine of  the  same  cylinder  dimensions  but  with 
the  cylinders  cast  in  pairs  or  in  block.  But  this  ad- 
ditional length  is  not  an  altogether  bad  feature.  It 
gives  much  greater  clearance  within  the  engine, 
greatly  facilitating  the  removal  and  the  replace- 
ment of  the  piston  and  connecting  rod  assem- 
blies, etc.  At  the  same  time,  considering  again 
the  high  prevailing  temperatures,  it  is  a  well- 
known  fact  that  the  individually  cast  cylinders 
make  possible  the  employment  of  cooling  jackets 
of  substantially  equal  cooling  capacity  at  all 
points  around  the  cylinder,  so  that  warping  of 
the  cylinders  resulting  in  misalignment  of  the 
working  parts  and  greatly  increased  wear  is,  to 
a  greater  or  less  extent,  done  away  with. 

In  the  engine  under  consideration,  the  cylinder 
heads  are  cast  with  the  cylinders  and  are  not 
separable ;  and  the  valve  arrangement  is  of  the 
L-head  type.  The  sectional  view  of  the  two  for- 
ward cylinders  clearly  indicates  the  symmetry  of 
the  water  jackets  as  pointed  out  above.  The 
cylinders  are  provided  with  flanges  at  the  lower 
ends  and  through  these  flanges  pass  the  cylinder 
hold-down  bolts  by  means  of  which  the  cylinders 
are  held  firmly  in  place  on  the  crankcase  casting. 
In  tractor  practice,  due,  of  course,  to  the  fact 
that  reduced  weight  is  not  of  prime  importance, 
the  ,crankcase  is,  in  almost  all  cases,  formed  of 
cast-iron  instead  of  aluminum,  which  is  usually 
employed  on  automobile  engines.  This  fact  is 
of  greater  importance  in  the  case  of  an  engine 
fitted  with  individually-cast  cylinders  than  is  so 
with  the  cast-in-block  type,  for  the  very  good 
reason  that  with  the  latter  the  cylinder  block 


32 


Tractor  Engines. 


Fig.  20. 
oil  engine. 


7}4x9,  four-cylinder  Twin  City 
Valve  side. 


itself  acts  as 
a  stiffen- 
ing  truss  to 
give  rigidity 
to  the  entire 
engine  struc- 
ture ;  while 
in  the  latter 
case  this 
function  must 
be  performed 
in  its  entirety 
by  the  crank- 
case  casting, 
together  with 
the  crankcase  lower  half. 

It  will  be  noticed  also  that  the  individually- 
cast  cylinder  construction  necessitates  the  em- 
ployment of  separate  manifolds  for  the  introduc- 
tion of  the  mixture  into  the  cylinders,  for  the 
exhaust  of  the  spent  gases  from  the  cylinders 
and  for  the  intake  of  the  water  to  the  jackets 
and  the  outlet  of  the  water  from  the  jackets  to 
the  radiator. 
From  this 
s  t  andpoint 
the  construc- 
tion is  not 
equal  to  the 
cast -in -block 
arrangement 
wherein  it  is 
perfectly  pos- 
sible to  mold 
the  entire  set 
of  gas  and 
water  pas- 
sages so  as  to 


Fig.    21. 
oil  engine. 


7^4x9   four-cylinder  Twin    City 


Features  of  Construction.  33 


be  incorporated  within  the  single  casting.  While 
the  casting  of  such  a  block  is  quite  a  costly  oper- 
ation, machining  is  simplified,  assembly  greatly 
simplified,  and  the  number  of  parts  greatly  re- 
duced, so  that  in  the  final  analysis  the  cast-in- 
block  construction  is  undoubtedly  the  cheaper. 

In  Figures  20  and  21  are  illustrated  two  views 
of  the  Twin-City  oil  engine  as  employed  on  one 
of  these  famous  tractors.  It  will  immediately 
be  noted  that  the  construction  of  this  engine  is 
not  greatly  different  from  that  of  the  Reeves  en- 
gine just  described,  the  most  noticeable  differ- 
ence being 
found  in  the 
arrangement 
of  the  mani- 
folds.  The 
peculiar  a  r  - 
rangement,  as 
indicated  o  n 
the  Twin- 
City  engine, 
has  been 
adopted  pri- 
marily with  a 
view  of  facilitating  the  burning  of  heavy  fuel 
such  as  kerosene;  the  arrangement  is  such  that 
some  of  the  exhaust  heat  is  utilized  to  effect 
full  vaporization  of  the  heavy  and  less  volatile 
ends  of  the  fuel  so  that  a  mixture  which  is 
readily  ignited  and  burns  to  completion  is  sup- 
plied to  the  engine  cylinders.  As  will  be  pointed 
out  in  the  chapter  bearing  on  carburetion,  it  is 
in  the  arrangement  of  the  passages  to  effect  this 
purpose  -that  are  discovered  one  of  the  chief  lines 
of  divergence  in  tractor  engine  practice. 

It  was  noted  before  that  six-cylinder  engines 
were  commonly  met  with  in  tractor  work  and 


Fig.  22.      7  J4x9  six-cylinder  oil  engine. 


34 


Tractor  Engines. 


the  Twin-City  line  is  one  of  several  in  which  this 
type  of  engine  is  employed.  The  Twin-City  Six 
is  illustrated  in  Figure  22  and  will  immediately 
be  recognized  as  exactly  the  engine  described 
above  with  the  addition  of  two  more  cylinders. 
It  is  because  the  individually-cast  cylinder  ar- 
rangement makes  possible  the  expansion  of  a 
four-cylinder  engine  into  a  six-cylinder  job  in 
this  manner  with  the  use  of  parts  which  are 
interchangeable,  with  a  very  few  exceptions, 


Fig.  23.  The  Tracklayer  Motor  is  the  valve-in-head  type,  long 
established  as  the  most  powerful  design  of  gas  motor. .  It  is  built 
along  simple  lines  to  stand  the  test  of  work  and  time. 

with  those  of  the  four-cylinder  engine  that  many 
tractor  manufacturers  prefer  this  construction. 
All  of  the  parts  on  this  six-cylinder  engine,  for 
instance,  with  the  exception  of  the  crankshaft, 
crankcase,  camshaft  and  manifolds,  are  perfectly 
adapted  to  the  four-cylinder  engine.  The  crank- 
shaft, of  course,  is  of  the  120  degree  type,  and 
is  mounted  on  seven  bearings. 


Features  of  Construction. 


35 


FIG.  24 


Fig.  24.     Two  views  of  the  Flour  City  engine. 
Above — Showing  camshaft  side  of  motor. 
Below — Showing  manifold  side  of  motor. 


36 


Tractor  Engines. 


Still  another  example  of  the  individually  cast 
cylinder  arrangement  on  a  four-cylinder  vertical 
motor  is  given  in  Figure  23.  This  is  the  Best 
Tracklayer  engine  employed  on  the  larger  of  the 
two  models  put  out  by  the  C.  L.  Best  Tractor  Co. 
and  is  of  clean-cut  rugged  construction.  It  will 
be  noticed  that  the  valve  arrangement  is  of  the 
valve-in-head  type  and  that  unlike  the  Reeves 
and  Twin-City  engines,  the  cylinder  heads  are 
cast  separately  and  held  in  place  by  hold-down 
bolts  or  cap  screws.  This  not  only  facilitates 

work  inciden- 
tal to  the  re- 
moval of  car- 
bon when  this 
operation  i  s 
necessary,  but 
it  also  makes 
the  frequent- 
ly necessary 
task  of  valve 
grinding  very 
much  easier. 

As  a  com- 
promise, not 
a  few  manu- 
facturers o  f 
four -cylinder 
engines  p  r  e- 
fer  to  employ  the  cast-in-pair  cylinder  construc- 
tion. Figure  24  illustrates  both  sides  of  the 
Flour  City  tractor  engine  which  is  of  this  type. 
It  gives  a  very  clean-cut  engine,  even  despite  the 
fact  that  outside  manifolds  are  necessary,  while 
at  the  same  time  the  close-coupling  of  the  two 
pairs  of  cylinders  makes  possible  the  employ- 
ment of  a  three-bearing  crankshaft  instead  of  the 
five-bearing  type  called  for  by  the  individually- 


Fig.   25.     The  cylinders  of  the   Neverslip 
engine  are  cast  in  pairs. 


Features  of  Construction.  37 


•'. 


cast  arrangement,  and  adds  materially  to  the 
stiffness  of  the  construction,  while  at  the  same 
time  reducing  production  costs.  In  cases  where 
the  cast-in-pair  practice  is  adopted  it  is  usual  to 
include  in  the  line  of  engines  a  two-cylinder 
model,  a  four-cylinder  model  and  a  six-cylinder 
model,  all  using  the  same  cylinder  blocks. 

Like  the  Best  engine,  the  Flour  City  engine  is 
of  the  valve-in-head  type,  and  is  novel  in  that 
very  large  inspection  plates  are  provided  on  both 
sides  of  the  cooling  jackets  by  means  of  which 

cleaning  of 
the  cooling 
system  can  be 
effected 
to  the  entire 
satisfaction 
of  the  oper- 
ator. 

Another  ex- 
ample of  the 
pair-cast  type 
i  s  illustrated 
in  Figure  25. 
This  is  the 
engine  employed  on  the  Neverslip  tractor,  made 
by  the  Monarch  Tractor  Co.,  Hartford,Wis.  It 
differs  from  the  Flour  City  job  materially,  being 
of  the  L-head  type  with  valves,  manifolds,  mag- 
neto, pump  and  governor  all  mounted  on  the  one 
side  of  the  engine. 

The  clean-cut,  staunch  design  made  possible 
by  the  cast-in-block  arrangement  is  well  illus- 
trated in  Figure  26,  which  pictures  the  four- 
cylinder  Kermath  engine  employed  on  the 
smaller  tractor  put  out  by  the  Monarch  Tractor 
Co.  under  the  style  Lightfoot.  The  engine, 
which  is  of  the  L-head  type,  is  remarkably  free 


Fig.  26.     Kermath  engine  used  in  Light- 
foot  tractor. 


38 


Tractor  Engines. 


Fig.    27.      15    H.    P.    motor    used 
by  Aultman-Taylor. 


from  complication  in 
so  far  as  external  ap- 
paratus is  concerned, 
which,  of  course,  is 
distinctly  a  desirable 
feature. 

Contributing 
greatly  to  this  end  is 
the  fact  that  the  sin- 
gle block  casting, 
coupled  with  the  L- 
head  valve  arrange- 
ment, makes  it  quite 

a  simple  matter  to  enclose  the  valve  mechanism 
entirely  by  means  of  a  side  plate  or  two  as  is 
indicated  in  Figure  27,  giving  a  view  of  one  of 
the  Aultman-Taylor  engines.  In  the  illustration 
the  forward  valve-enclosing  plate  has  been  re- 
moved, disclosing  the  valve  stems,  springs  and 
tappet  mechanism  of  the  two  forward  cylinders. 
Such  enclosure  is,  of  course,  desirable  from  the 
standpoint  of  cleanliness,  which  means  reduced 
wear;  as  well  as  from  the  standpoint  of  better 
lubrication  of 
this  important 
part  of  t  h  e 
engine  mech- 
a  n  i  s  m .  In 
most  cases, 
for  instance, 
the  tappets 
and  the  valve 
stems  are 
lubricated  by 
an  oil  mist 
conducted  in- 
to the  valve 


Fig.    28.      6^x8,    four-cylinder    Twin 
City  oil  engine.     Valve  side. 


Features  of  Construction.          39 

chamber  from  the  crankcase  through  suitable 
drillings  or  through  holes  bored  in  the  hollow 
tappets,  providing  a  sufficient  amount  of  oil  for 
the  purpose.  This,  too,  means  reduced  wear  and 
higher  efficiency. 

Contrasting  the  Twin  City  engine  shown  in 
Figure  28  with  those  illustrated  in  Figures  20 
and  21  shows  clearly  the  trend  of  design.  The 
6j4  by  8  inch  engine  shown  in  the  last  figure  is 
a  later  production  and  incorporates  many  fea- 
tures of  design  not  found  in  the  earlier  types, 
such,  for  instance,  as  the  enclosed  valves,  the 
block-cast  cylinders  and  the  separable  cylinder 
head.  Quite  naturally,  the  over-all  length  of  the 
engine,  due  to  the  compact  cylinder  arrangement, 
is  greatly  reduced,  as  a  comparison  of  the  two 
types  offered  by  Twin  City  clearly  indicates. 

It  might  be  well  to  point  out  at  this  stage  that 
the  manufacturer  of  the  Twin  City  line  of  trac- 
tors is  one  of  the  most  progressive  in  the  indus- 
try. The  later  models  of  the  Twin  City  tractors, 
which  are  giving  a  remarkable  account  of  them- 
selves in  the  field,  and  especially  at  the  tractor 
demonstrations  throughout  the  country,  are  sot 
far  in  advance  as  to  be  equipped  with  "double" 
valves ;  that  is,  two  inlet  valves  and  two  exhaust 
valves  to  the  cylinder,  closely  following  aviation 
engine  practice.  Thereby  greater  area  is  ob- 
tained than  is  possible  with  the  single  valve  ar- 
rangement, and  the  flow  of  the  gases  is  corre- 
spondingly facilitated.  This,  in  turn,  results  in 
a  marked  power  increase  and  cooler  operation ; 
not  the  least  important  improvement  in  the  oper- 
ation, however,  and  one  that  is  immediately  ap- 
parent and  highly  important,  is  the  fact  that 
these-  engines  will  throttle  down  and  idle  on 
kerosene  fuel  in  a  manner  that  leaves  but  little 
to  be  desired.  It  is  lamentable,  but  true,  that 


40 


Tractor  Engines. 


this  much  cannot  be  said  for  all  kerosene  en- 
gines employed  in  modern  tractor  construction. 
Also  reflecting  modern  practice  to  a  marked 
degree  is  the  engine  illustrated  in  two  views  in 
Figure  29,  employed  on  the  Emerson-Branting- 


MG.29 


Figure  29.     Emerson-Brantingham  Engine. 

Above — Right  side  of  E-B  16  H.  P.  kerosene  motor,  showing 
carburetor  and  governor. 

Below — Left  side  of  E-B  16  H.  P.  kerosene  tractor,  showing 
magneto,  pump  and  manifolds. 

ham  16.  It  will  be  seen,  in  the  lower  view,  that 
the  valves  are  fully  enclosed  by  a  single  plate,  the 
valve  arrangement  being  of  the  L-head  type. 


Features  of  Construction.  41 


Fig.   30. 
side)  4^4 


Buda  Model   "HU"   (exhaust 
in.     (107.94x139.66  MM.) 


One  of  the 
factors  which 
has  contributed 
greatly  to  the 
rapid  advance- 
ment of  the 
automobile  was 
the  coming 
of  the  parts 
specialist  —  the 
manufacturer 
with  plant 
equipped  to 
make  motors, 
and  who  concentrated  on  motors  and  developed 
an  engine  that  matched  the  best ;  similarly  the 
manufacturer  who  specialized  on  transmissions, 
axles,  carburetors,  magnetos,  etc.,  etc.  These 
specialists  could  well  afford  to  employ  the  best 
of  talent  in  their  particular  lines,  talent  that  the 
average  automobile  manufacturer  could  not  begin 
to  hire;  as  a  result,  the  industry  as  a  whole  pro- 
gressed by  leaps  and 
bounds. 

It  is  not  hard  to 
predict  that  the  en- 
trance of  the  specialist 
into  the  field  of  tractor 
production  will  have  a 
similar  elevating  effect. 
At  the  present  stage  of 
the  industry,  the  special 
manufacturer  of  en- 
gines adapted  particu- 
larly for  tractor  service 
has  gained  a  firm  foot- 
ing and  tractor  engine 
design  is  making 


FIG. 31 


Fig.  31.  Buda  Model  "HU" 
(end  view)  4^  in.  x  Sy2  in. 
(107.94  x  139.66  MM.) 


42 


Tractor  Engines. 


marked  prog- 
ress. 

One  of  the 
most  impor- 
tant stock  en- 
engine  tnanu- 
facturers  is 
the  Buda  Co., 
of  Harvey, 
111.  _Well 
known  also 
as  automobile 


J  FIG. 32 


Fig.   32.     Waukesha  tractor  engine. 


engine  manu- 
facturers— 
and  one  of  its  typical  tractor  engine  offerings 
is  illustrated  in  Figures  30  and  31.  It  is  a  four- 
cylinder,  block-cast,  L-head  job,  clearly  reflect- 
ing the  best  that  automobile  engine  practice 
affords  a*nd  is  being  successfully  used  by  dozens 
of  tractor  manufacturers.  Its  clean-cut  appear- 
ance and  apparent  simplicity  are  its  major  appeal. 
Figures  32  and  33  illustrate  the  Waukesha  en- 
gine, which  is  another  of  the  stock  engine  jobs 
which  is  a  big  factor  in  the  industry.  It 

also  is  a  four-cylin- 
der, L  -  head  engine 
with  the  valves  fully 
enclosed ;  the  cylin- 
ders, however,  are 
cast  in  pairs  instead 
of  in  a  single  block, 
as  was  the  case  with 
the  Buda  engine. 

Some  of  the  other 
stock  tractor  engines 
of  prominence  are  the 

Climax,  Wisconsin,  Buffalo,  Beaver,  Erd,  Gile, 
Doman,  Westman  and  Midwest. 


FIG.33 


Fig.  33.     Waukesha  Motor 
used  in  the  Nilson  Senior. 


CHAPTER  III. 

J/Lajor  Engine  Parts. 

Their  Construction,  Functions,  Care  and  Repair 
Fully  Described. 

WHILE  with  some  automotive  engines  in 
applications  other  than  tractor  work,  ma- 
terial other  than  cast-iron  or  semi-steel  may  be 
used  for  cylinder  construction,  in  tractor  prac- 
tice these  materials  only  are  employed.  The 
reasons  are  not  hard  to  find;  the  material— 
semi-steel  is  cast-iron  with  a  certain  proportion 
of  steel  added  to  give  it  toughness — is  easily 
cast,  easily  machined,  and  when  suitably  de- 
signed and  treated  in  manufacture  will  resist 
any  tendency  to  warp  under  the  heat  and  will 
carry  all  strains  imposed  upon  it.  It  has  still 
another,  and  an  all-important  virtue.  This  is  the 
fact  that  there  is  present  in  cast-iron  a  certain 
proportion  of  graphite  in  combination  with  the 
metal  itself.  Under  rubbing  action  the  smooth 
cylinder  bore  assumes  a  high  polish  and  a  tough 
film  forms  which  resists  wear  to  a  remarkable 
degree. 

In  almost  all  cases,  as  was  made  plain  in  the 
preceding  chapter,  the  cylinder  cooling  jacket  is 
cast  integral  with  the  cylinder  itself  and  the 
modern  tendency  is  to  form  all  cylinders  in  a 
single  casting  with  integral  jackets  and  mani- 
folds. The  removable  cylinder  head,  however, 
bolted  to  the  top  of  the  cylinder  casting  is  taking 
on  a  significance  it  never  had  before,  and  many 
manufacturers  ane  incorporating  it  in  their  de- 
signs. Such  a  cylinder  casting  with  removable 

(43) 


44  Tractor  Engines. 

head  is  shown   in  Figure  34,   from  one  of  the 
Rumely  models. 

In  the  past  it  has  been  common  practice  to 
rough-bore  the  cylinders  and  ream  them  to  a 
finish,  which  although  not  perfectly  smooth,  soon 
assumed  a  polish  under  the  piston  action.  This 
practice,  however,  is  fast  giving  way  to  the 
grinding  process,  which  leaves  the  cylinders  with 
highly  polished  and  perfectly  true  round  walls, 
greatly  facilitating  fitting  the  pistons  with  the 
proper  clearance  and  checking  any  tendency  for 
oil  pumping  and  gas  "blow-by"  when  the  engine 

is  in  operation.  With 
a  large  number  of  the 
stock  engine  manu- 
facturers, it  is  also 
common  practice  to 
"weather"  the  cylin- 
ders for  some  months 
after  the  first  machin- 

Fig.  34.   Rumely  cylinders  ing     Operation.         This 

and  cylinder  head. 


riG.34 


^ 

ders  are  allowed  to  age  in  the  open,  which  has 
the  effect  of  relieving  any  internal  strains  set 
up  as  a  result  of  the  casting  process  and  the 
machining  process,  and  which  entail  warping  of 
the  cylinders  and  wear.  / 

Care  of  the  Cylinders.  —  Provided  the  engine 
is  treated  with  a  fair  degree  of  consideration, 
especially  as  to  proper  lubrication,  the  wear  on 
the  cylinders  will  be  comparatively  slight  and 
altogether  negligible  for  the  first  season  or  two. 
When  the  cylinders  do  show  signs  of  wear,  pro- 
vided it  is  even  throughout  the  length  of  the 
bore,  and  on  all  sides  —  such  a  condition  is  very 
rare  because  of  the  variation  in  piston  pressure 
against  the  walls  at  different  parts  of  the  stroke  — 


Major  Engine  Parts. 


45 


correction  can  be  effected  by  fitting  oversize  pis- 
tons supplied  by  the  manufacturer  a  few  thou- 
sandths of  an  inch  larger  than  the  ordinary  piston. 

To  fit  the  new  pistons 
properly  it  will  be  nec- 
essary to  take  the  en- 
gine down  and  lap  the 
cylinders    with   an    ex- 
panding lap,  which  can 
be  very  easily  made  as 
illustrated     in     Figure 
35,  from  one  of  the  old 
pistons.     The  abrasive 
material  for  this  work 
is    a    mixture    of    very 
finely  ground  glass  and 
machine  oil.     It  should 
be  used  sparingly.    The 
proper   lapping   motion 
is  a  combined  twist  and 
up  -  and  -  down    stroke 
throughout    the    entire 
length  of  the  cylin- 
der, so  that  all 
parts  of  the 
walls     will    be 
evenly  ground ; 
the  lap  should 
be  turned  from 
time  to  time  to 
bring  new  sur- 
faces into  con- 
tact.    The  lap 
should  be  kept 
expanded    and 
working     until 

the   force   re-  Fig>     35>      Illustrating     construction 

and   use   of  an   expanding  lap   for   con- 
tO    turn        ditioning  the  cylinder  bores  after  wear. 


46 


Tractor  Engines. 


or  move  the  lap  is  practically  constant  through- 
out the  stroke.  This  shows  that  the  cylinder  is 
perfectly  round.  Care  should  be  taken  to  see 
that  all  cylinder  wall  scores  have  been  removed. 
Where  the  cylinder  walls  are  badly  worn  or 
are  scored,  due  to  lack  of  adequate  lubrication, 
or  the  presence  of  some  abrasive  like  sand,  which 
has  damaged  the  cylinder  wall  surface,  reboring 
and  fitting  oversize  pistons  are  necessary.  Re- 
boring  a  cylinder  is  a  job  which  calls  for  special 
tools  and  for  a  practiced  machinist  to  operate 
them  in  order  to  turn  out  creditable  work.  It  is 
highly  inadvisable  for  the  average  tractor  owner 
or  operator  to  undertake  this  work  himself.  The 
best  plan  is 
to  send  the 
cylinder,  or 
the  cylinder 
block,  as  the 
case  may  be, 
to  the  nearest 
service  sta- 
tion of  the 
tractor  manu- 
facturer or  to 
some  compe- 
tent tractor  repairman 
job  of  it. 


Fig.  36.  Cylinder  cut  out  to  show  how 
the  Avery  inner  cylinder  wall  may  be  re- 
moved. 


who  will  make  a  proper 
The  Avery  cylinder  can  be   readily 
relined  as  shown,  in  Figure  36. 

It  sometimes  happens  that  the  piston  pin  will 
work  loose  and  will  chisel  a  slot  in  one  or  both 
sides  of  the  cylinder  wall  too  deep  to  be  removed 
by  reboring.  Less  frequently  a  piston  ring  will 
break  and  produce  a  like  result,  the  sharp  broken 
edge  chiseling  a  groove  in  the  wall.  In  such  an 
instance  a  recently-developed  welding  process, 
called  the  Lawrence  process,  is  invoked  to  fill  up 
the  groove,  the  excess  metal  then  being  ground 


Major  Engine  Parts.  47 

flush  and  lapped  to  a  surface  true  with  the  bal- 
ance of  the  cylinder  wall.  This  also  is  a  job 
for  the  expert;  when  it  is  employed,  unless  the 
cylinders  are  badly  worn,  it  is  usually  not  neces- 
sary to  fit  oversize  pistons. 

In  the  case  of  a  cracked  cylinder,  due  to  neg- 
lect in  winter,  with  consequent  freezing  of  the 
cooling  water  and  cracking  of  the  cooling  jacket, 
welding  is  the  accepted  means  of  effecting  a  per- 
manent repair.  Care  should  be  exercised  in  the 
selection  of  a  competent  welder  for  this  work, 
as  a  man  who  is  inexperienced  in  handling  his 
torch  will  warp  the  cylinder  or  the  block  out  of 
shape  and  ruin  it  for  further  use.  A  good  welder, 
however,  can  make  a  very  satisfactory  repair 
even  on  a  very  badly  cracked  cylinder.  * 

There  are  several  compounds  now  on  the  mar- 
ket for  mixing  with  the  cooling  water  which  are 
adapted  to  harden  on  contact  with  the  air  and 
thus  cement  any  cracks  in  the  cooling  system 
through  which  they  are  carried  by  the  water. 
Any  one  of  these  compounds  which  is  free  from 
solid  matter  may  be  employed  as  a  temporary 
means  of  repairing  a  cracked  cylinder  jacket 
when  it  is  not  convenient  to  take  the  engine  down 
for  welding ;  in  fact,  in  many  instances  this 
method  of  repair  has  been  found  so  satisfactory 
as  to  preclude  the  necessity  of  a  permanent  repair. 

With  any  tractor  engine  it  will  be  necessary 
to  remove  the  accumulation  of  carbon  from  the 
walls  of  the  combustion  chamber,  the  valve  heads 
and  the  tops  of  the  pistons  once  or  twice  during 
the  season.  The  tendency  to  deposit  carbon  is 
a  chronic  ailment  with  which  all  internal  combus- 
tion engines  are  afflicted  to  varying  degrees,  de- 
pending on  operating  conditions,  fuel  used,  pro- 
portioning of  the  mixture,  condition  of  the 
engine — especially  as  to  piston  and  piston  ring 


48 


Tractor  Engines. 


fit, — character  and  grade  of  oil  used  for  lubri- 
cation, etc. 

When  all  is  said  and  done,  the  best  method 
of  removing  the  carbon  is  to  take  the  engine 
down  far  enough  to  get  at  the  deposit,  and  then 
scrape  it  off  with  special  carbon-scraping  tools 
made  up  for  this  purpose  and  so  shaped  that 
the  blunt  knife  edge  can  be  worked  into  every 
nook  and  corner  and  the  last  trace  of  the  trouble- 
some carbon  deposit  removed. 

With  engines  equipped  with  separable  cylinder 
heads  this  is  not  a  hard  job  at  all,  for  by  unbolt- 
ing the  head  (Figure  37) — removing  the  neces- 
sary parapher- 
nalia, such  as 
water  m  a  n  i- 
folds,  ignition 
cables,  etc.,  and 
after  draining 
the  cooling 
system  —  the 
entire  combus- 
tion chamber 
is  exposed. 
Under  any  cir- 
cumstances it 

will  be  found  that  the  employment  of  a  steel  wire 
brush,  or  a  piece  of  steel  wool,  will  considerably 
aid  in  removal  of  the  deposit  unless  it  be  of  the 
"tacky"  kind;  then  hard  scraping  is  the  only 
resort.  Where  the  cylinder  heads  are  not  sep- 
arable, it«is  sometimes  possible  to  employ  flexible 
wire  carbon  scrapers,  getting  at  all  parts  of  the 
combustion  chamber  through  the  valve  cap  open- 
ings, and  finally  blowing  the  accumulation  of 
carbon  flakes  out  of  the  cylinder  with  an  air 
blast.  Of  course,  on  an  engine  of  this  type,  if 
an  oxygen  burning  apparatus  is  available,  a  much 


Fig.  37.     Avery  separable  cylinder  head. 


Major  Engine  Parts.  49 

cleaner  job  can  be  effected  by  burning  than  by 
attempting  to  scrape  through  the  valve  cap  holes, 
which  at  best  is  a  makeshift  method. 

After  thoroughly  scraping  the  piston  tops  and 
combustion  chamber  walls,  in  the  case  of  the 
separable  head  engine,  before  replacing  the  head 
casting,  see  that  there  is  no  carbon  on  the  valve 
seats  and  make  sure  that  the  cylinder  head  gasket 
is  in  good  condition.  Replace  the  gasket  in 
proper  position;  it  is  best  to  put  it  back  without 
shellac.  Replace  the  cylinder  head  casting  and 
bolt  it  down  in  place,  making  sure  to  draw  up 
gradually  on  the  bolts  all  around  the  casting  so 
as  to  distribute  the  strain  evenly.  Never  tighten 
up  to  the  limit  on  one  bolt  with  the  others  all 
loose ;  take  a  few  bites  on  each  and  work  them 
in  rotation  until  all  are  drawn  up  snugly. 

With  the  engine  all  assembled,  run  it  for  a 
while  to  warm  the  jackets  thoroughly,  and  then 
apply  the  wrench  to  the  cylinder  head  bolts  again 
and  draw  them  up,  taking  up  all  the  slack  which 
has  developed  due  to  expansion  under  the  heat. 

Like  the  cylinders,  the  pistons  are  also  made 
of  cast-iron  and  are  carefully  turned  down  to  a 
size  wlfich  permits  of  a  slight  clearance  between 
the  piston  and  the  cylinder  wall.  This  clearance 
varies  with  different  engines,  but  it  can  generally 
be  accepted  as  one-thousandth  of  an  inch  for 
each  inch  of  diameter  of  the  piston,  the  clearance 
being  measured  on  the  skirt  of  the  piston;  the 
skirt  is  the  lower  section.  As  a  rule,  the  clear- 
ance at  the  top  of  the  piston  will  be  somewhat 
larger  than  this,  due  to  the  fact  that  the  top  of 
the  piston  is  subjected  directly  to  the  heat  of  the 
burning  gases  and  becomes  considerably  hotter 
than  the  skirt,  and  as  a  result  expands  more. 

The  function  of  the  clearance  is  quite  obvious. 
The  piston,  not  being  water-cooled  like  the  cylin- 


50 


Tractor  Engines. 


der  walls,  will  reach  a  higher  temperature  under 
operative  conditions  than  the  latter  and  will  con- 
sequently increase  in  diameter  at  a  more  rapid 
rate  than  will  the  cylinder  bore.  The  clearance 
is  left  so  that  the  piston,  even  when  heated  up  to 
maximum  temperature,  will  always  fit  loosely 
enough  in  the  bore  to  slide  freely,  with  no  ten- 
dency to  bind  or  seize.  Regardless  of  the  tem- 
perature attained, 
however,  some 
clearance  is  always 
present  between  the 
piston  and  the  cyl- 
inder wall. 

That  being  the 
case,  it  is  apparent 
that  there  will  be  a 
tendency  for  the 
gases  to  rush  past 
the  piston  through 
this  space  on  the 
compression  and 
power  strokes ; 
also  for  the  air  in 


crankcase    to 
up    into    the 


Fie;.  38.  Section  of  piston  show- 
ing ring  slots,  bosses,  webs,  piston 
pin  and  connecting  rod  eye. 


the 
rush 

combustion  cham- 
ber on  the  intake 
stroke.  In  order  to 
counteract  this  ten- 
rush  past  the  piston, 


dency  for  the  gases  to 
the  pistons  are  slotted,  as  shown  in  Figure  38, 
and  into  these  slots,  which  are  of  uniform 
depth  all  around  the  piston,  are  fitted  expandable 
rings,  called  piston  rings. 

The  piston  rings  are  cast-iron  rings,  generally 
eccentric  in  form  and  slotted  or  split  at  the  nar- 
rowest point.  The  rings  are  turned  down  to  the 


Major  Engine  Parts.  51 

exact  diameter  of  the  cylinder  bore  on  the  out- 
side before  slotting.  When  slotted,  therefore, 
they  expand  slightly  and  can  be  sprung  into  posi- 
tion in  the  slots  on  the  piston.  With  most  trac- 
tor engines,  three  rings  are  fitted,  although  in 
some  cases  four  and  even  five  are  employed. 
Their  peculiar  shape  and  the  character  of  the 
metal  makes  them  springy  and  resilient,  and  the 
gradually  increasing  section  from  the  split  or 
slot  to  the  largest  section  diametrically  opposite 
it  insures  equal  tension  at  all  points  on  the 
periphery  of  the  ring. 

In  position  on  the  piston  and  with  the  piston 
in  the  cylinder,  the  rings  expand  outward  against 
the  cylinder  wall,  closing  up  the  clearance  space 
left  between  the  piston  and  the  cylinder  wall, 
and  thereby  prevent  the  loss  of  the  gases  and  the 
blow-by  of  air.  The  rings  also  take  a  good  part 
of  the  wear,  distribute  the  oil  on  the  cylinder 
walls,  and  check  the  passage  of  oil  past  the  piston 
and  into  the  combustion  chamber  in  excess ;  they 
tend  to  cushion  the  "cant"  or  "slap"  of  the  piston 
at  each  end  of  its  stroke  due  to  reversal  of  mo- 
tion and  the  angle  of  the  connecting  rod. 

The  lower  ring  is  usually  called  the  "wipe" 
ring,  due  to  the  fact  that  it  scrapes  off  the  excess 
oil  from  the  cylinder  wall  and  returns  it  to 
the  crankcase  chamber.  Where  the  wipe  ring 
is  fitted  below  the  piston  pin,  it  usually  is  posi- 
tioned quite  low  on  the  piston,  so  that  it  just 
overruns  the  counterbore  at  the  lowest  part  of 
the  cylinder  bore — the  counter  bore  is  the  tapered 
section  of  the  bore  so  formed  as  to  facilitate 
replacement  of  the  pistons  by  compressing  the 
rings  and  preventing  them  from  catching  or  jam- 
ming. The  reason  for  the  wipe  ring  overrunning 
the  counterbore  is  so  that  the  ofl  it  carries  down 
will  have  ample  passageway  back  to  the,  crank- 


52  Tractor  Engines. 

case  chamber  and  will  not  be  returned  to  the 
upper  part  of  the  cylinder  wall  by  the  upward 
movement  of  the  piston. 

Where  the  wipe  ring  is  positioned  above  the 
piston  pin,  and  in  a  few  instances  where  it  is 
located  well  down  on  the  skirt,  this  same  func- 
tion is  performed  in  another  manner.  Immedi- 
ately below  the  wipe  ring  is  turned  an  oil  relief 
groove,  generally  triangular  in  cross-section.  The 
oil  scraped  off  by  the  wipe  ring  collects  in  this 
relief  groove  and  is  returned  to  the  crankcase 
chamber  through  a  series  of  holes  which  carry 
it  to  the  inside  of  the  hollow  piston. 

The  piston  is  provided  with  two  bosses  on  the 
inside,  into  which  is  fitted  a  hollow  steel  pin 
called  the  piston  pin  or  "wrist"  pin,  and  which 
serves  to  connect  the  piston  to  the  upper  end  of 
the  connecting  rod.  The  pin  is  made  of  com- 
paratively soft  steel,  but  very  tough  in  nature, 
so  that  it  is  well  adapted  to  stand  up  under  the 
constant  shock  encountered  under  the  explosions 
without  becoming  brittle  and  snapping,  due  to 
crystallization.  But  as  the  piston  pin  must  also 
take  a  certain  amount  of  heavy  bearing  wear, 
due  to  the  oscillation  of  the  rod  with  the  engine 
in  operation,  it  is  obvious  that  its  outer  surface^ 
must  be  well  adapted  to  resist  this  wear.  Con- 
sequently, the  pin,  after  being  rough  shaped  to 
size,  is  "cjase  hardened" — that  is,  it  is  subjected 
to  a  heat  treating  process  which  leaves  the  outer 
shell  very  hard  and  wear-resisting  to  a  depth  of 
from  two  to  five  thousandths  of  an  inch ;  then  the 
pin  is  finished  to  exact  size  by  grinding.  This 
hard  shell  takes  the  bearing  wear,  while  the  tough 
core  carries  the  brunt  of  the  explosive  pressure. 

In  some  instances,  the  pin  is  clamped  fast  in 
the  upper  end  ofv"eye"  of  the  connecting  rod 
and  allowed  to  find  a  bearing  in  the  piston  bosses ; 


Major  Engine  Parts.  53 

in  other  cases,  the  pin  is  made  fast  in  the  bosses 
by  pinning  or  by  a  set-screw  or  other  means  of 
locking  and  the  bearing  is  in  the  eye  of  the  rod. 
In  the  latter  case  the  eye  is  always  bushed  with 
a  bronze  bushing  which  takes  the  wear.  In  the 
first  case,  however,  as  a  rule  the  bosses  are  not 
bushed,  since  the  cast-iron  material  of  the  boss 
provides  a  fine  wearing  surface.  In  a  few  in- 
stances, bronze  bushes  are  fitted  to  the  bosses. 

Internally,  most  pistons  are  provided  with  webs 
radiating  from  the  piston  head,  and  the  function 
of  these  webs  is  not  so  much  to  provide  addi- 
tional strength  and  support  to  the  piston  head, 
although  they  do  stiffen  up  the  bosses,  as  it  is  to 
assist  in  the  radiation  of  the  piston  head  heat  to 
the  air  in  the  crankcase  chamber  and  thereby 
maintain  the  piston  at  a  moderate  working  tem- 
perature. In  some  cases,  also,  the  piston  skirts 
are  provided  with  oil  grooves — just  shallow  slots 
— which  serve,  to  hold  a  quantity  of  lubricant  and 
distribute  it  evenly  over  the  cylinder  wall  surface. 

Care  and  Repair  of  Pistons. — The  pistons,  like 
the  cylinders,  are  subject  to  wear.  As  was  men- 
tioned ujider  the  section  dealing  with  cylinder 
repair,  the  usual  practice  is  to  replace  them  with 
new  oversize  pistons  when  they  show  wear  to  an 
excessive  degree  or  when  scored,  or  when  either 
-of  these  two  ailments  have  affected  the  cylinder 
bore.  This  is  necessary  to  secure  a  proper  fit. 

When  the  wear  is  not  excessive,  correction  can 
•  be  made  by  removing  the  piston  pin  and  detach- 
ing the  connecting  rod  and  then  heating  each 
piston  to  a  cherry  red  and  allowing  it  to  cool 
very  slowly.  The  heat  should  be  applied  evenly 
and  the  temperature  mentioned  should  not  be 
exceeded;  if  the  piston  is  cooled  too  quickly  it 
will  warp  out  of  shape.  If  properly  done,  the 
effect  will  be  to  expand  the  pistons  slightly,  and 


54  Tractor  Engines. 

they  will  be  enough  larger  than  they  were  orig- 
inally to  permit  of  lapping  down  to  a  proper  fit 
in  the  cylinders. 

The  lapping  is  accomplished  in  the  same  man- 
ner as  described  above,  with  the  exception  that 
in  this  case  the  piston  is  lapped  right  into  the 
cylinder  it  is  intended  to  use  it  in.  The  ground 
glass  and  oil  mixture  is  used  sparingly  and  lap- 
ping is  continued  until  when  dry  and  clean  the 
piston  moves  easily  throughout  the  length  of  its 
stroke  without  any  tendency  to  stick  or  bind ; 
.nor  will  it  bind  when  twisted  around.  After 
being  perfectly  fitted,  it  will  be  necessary  to  fit 
new  rings  to  the  piston. 

The  piston  ring  grooves  are  likely  to  be  worn 
after  long  use.  In  such  a  case,  it  will  be  found 
that  the  pistons  themselves  are  no  doubt  badly 
worn  so  that  replacement  is  necessary.  It  never 
pays  to  attempt  to  true  up  a  ring  slot  by  turning 
it  true  to  a  larger  size  in  the  lathe.  The  best  plan 
is  to  get  a  new  piston  and  fit  standard  size  rings 
to  it  in  the  manner  outlined  below. 

Piston  Rings.  —  The  piston  rings  will  wear 
both  on  their  peripheries  and  on  the  upper  and 
lower  edges,  so  that  they  will  become  a  "sloppy" 
fit  in  the  ring  grooves.  This  will  not  only  permit 
of  the  escape  of  the  compressed  gases  on  the 
compression  and  power  strokes,  but  will  also  . 
permit  the  oil  working  past  the  rings — or  rather 
in  behind  the  rings  and  then  up  above  them.  As 
a  matter  of  fact,  this  sloppy  condition  of  the 
rings  causes  them  actually  to  assist  in  elevating 
the  oil,  for  on  the  downward  stroke  of  the  piston 
the  rings  work  to  the  top  of  the  grooves,  leaving 
all  the  space  represented  by  the  original  clearance 
left  in  fitting,  and  the  subsequent  wear,  below  the 
under  side  of  the  ring,  the  lower  edge  of  which 
serves  to  scrape  the  oil  from  the  cylinder  walls 


Major  Engine  Parts.  55 

and  carry  it  through  this  space  to  the  pocket  in 
behind  the  ring.  When  the  piston  starts  on  its 
up  stroke,  the  ring  shifts  to  the  bottom  of  the 
slot,  leaving  the  space  at  the  top  through  which 
the  oil  is  pumped  by  the  ring  movement  and 
deposited  on  the  cylinder  walls  above  the  ring  to 
work  up  eventually  into  the  combustion  chamber, 
as  indicated  in  Figure  39. 

As  a  rule,  when  the  engine  is  taken  down, 
unless  it  has  seen  unusually  severe  service,  wear 
with  the  cylinders  and  pistons  will  not  be  appar- 
ent, or  at  least  so  appreciable  as  to  make  repairs 
necessary.  This,  however,  is  not  so  in  the  case 
of  the  piston  rings.  They  will  show  wear  in  two 
ways;  the  periphery  which  contacts  with  the 
cylinder  wall  may  be  streaked  with  black  lines 


Types  of  piston  rings  showing  how  oil  works  upward. 
Fig.    39.     Showing    oil    pocket    behind    piston    rings    and    how 
sloppy"  ring  fit  assists  in  oil  pumping. 


running  in.  a  vertical  direction,  showing  that-  the 
fit  is  poor  and  that  the  ring  has  not  been  in  con- 
tact with  the  cylinder  wall  all  the  way  around,  so 
that  the  gases  have  "blown  by"  the  rings,  leaving 
the  black  marks,  or  else  the  upper  and  lower  sides 
of  the  ring  may  be  worn  so  that  the  .rings  are  a 
loose  fit  in  the  ring  grooves  on  the  piston.  In  the 
former  case,  unless  the  blow-by  can  be  traced  to 
the  use  of  incorrect  grade  of  oil  which  has  not 
had  sufficient  body  to  maintain  a  perfect  piston 
ring  seal  under  the  heat,  thereby  preventing  -the 
escape  of  the  gases,  replacement  of  the  rings 
with  the  new  ones  will  be  necessary. 


56  Tractor  Engines. 

Sometimes,  where  it  is  found  that  even  the 
fitting  of  new  rings  does  .not  effect  a  cure,  it 
is  well  to  increase  the  pressure  per  unit  of  ring 
surface  on  the  cylinder  wall,  and  this  is  done  by 
the  very  simple  process  of  fitting  rings  with  a 
groove,  similar  to  an  oil  groove,  all  around  the 
periphery  which  cuts  down  the  surface  in  actual 
contact  with  the  wall.  As  the  total  ring  pressure, 
or  tension,  is  the  same  and  the  surface  over 
which  it  is  distributed  is  smaller,  it  stands  to 
reason  that  the  unit  pressure  is  increased  and 
the  ring  will  hold  the  gases  to  better  advan- 
tage. 

The  cost  of  new  piston  rings  is  so  low  that 
when  it  is  necessary  to  remove  the  rings  from 
the  ring  slots  for  any  reason  whatsoever,  it 
scarcely  will  be  worth  while  to  replace  the  old 
ones ;  it  is  much  better  to  fit  new  rings  all  around. 
Such  being  the  case,  there  is  scant  reason  for 
wasting  time  endeavoring  to  remove  the  rings 
whole;  they  are  very  brittle  and  can  be  broken 
and  readily  removed. 

If,  however,  it  is  desired  to  remove  the  rings 
without  breaking  them,  provide  short  strips  of 

sheet  brass  or  steel, 
about  22  or  2-i  gauge, 
one-half  inch  wide. 
With  a  screwdriver 
lift  the  end  of  the 
ring  and  slip  one  of 
these  metal  slips  un- 
der it,  as  indicated  in 
and  """""Figure  40,  working  it 
around  to  the  back 
with  the  aid  of  the  screwdriver.  Do  the  same  with 
one  of  the  other  slips,  using  the  remaining  slips 
to  carry  the  ends  of  the  ring.  For  the  top  ring, 
the  use  of  the  metal  slips  may  be  dispensed  with 


m 


R6.40 


Major  Engine  Parts. 


57 


if  you  work  gently  and  do  not  force  the  ring 
too  hard  with  the  screwdriver;  but  for  the  lower 
rings  they  are  necessary  in  order  to  bridge  -the 
upper  ring  slots,  so  that  the  rings  will  not  slip 
into  them  when  they  are  being  removed. 

Be  careful  in  removing  the  rings,  to  so  mark 
them  that  they  can  be  returned  to  the  same  ring 
grooves.  After  removal,  if  the  ring  slots  in  the 
piston  are  not  worn,  clean  out  the  carbon  deposit 
with  a  blunt  screwdriver,  or,  better  still,  with  a 

section  of  a  broken 
ring  which  has  been 
ground  off  to  a  chisel 
edge  as  indicated  in 
Figure  41.  Where 
the  rings  are  a 
sloppy  fit  in 
the  grooves  it 
is  essential  that 
they  be  re- 
placed  with 
new  ones 
which  should 
be  properly  fit- 
ted. A  good 
way  to  gauge 
the  fit  is  indi- 
cated in  Figure  40.  Take  the  new  ring  and  fit 
it  into  the  slot  as  shown.  If  it  is  a  proper  fit, 
there  will  be  just  an  appreciable  play  at  the  outer 
edge  of  the  ring  diametrically  opposite  the  point 
of  contact  with  the  piston ;  if  there  is  more  than 
just  an  appreciable  shake  or  movement,  try  an- 
other new  ring  to  this  slot  which  may  prove  a 
better  fit.  The  ring  should  be  rolled  all  the 
way  around  in  the  slot  and  the  fit  determined 
at  several  points.  If  it  is  found  that  the  ring 
is  too  snug  a  fit,  rig  up  a  trimming  board,  as  indi- 


Fig.     41.       Cleaning     ring    grooves 
sharpened  section  of  broken  ring. 


with 


58 


Tractor  Engines. 


cated  in  Figure  42,  covering  down  a  perfectly  \ 
true,  smooth  piece  of  board  with  very  fine  sand- 
paper.   The  ring  can  be  rubbed  down  to  a  proper 

__r_ .    fit  on  this,  pro- 

1   vided  that  the 
•  pressure  is  ex- 

•^•^g*./.  I   erted  evenly  on 

all  sides  of  the 
ring,  so  as  not 
to  cut  more  off 
one  side  than 
the  other  and 
so  disturb  the 
parallelism  of 
the  edges.  Af- 
ter a  ring  has 
been  fitted  to 
a  slot,  mark 
it  so  that  you  will  be  sure  and  place  it  in  the 
proper  slot.  When  very  close  fitting  is  desired, 
filing  on  a  special  ring^-holding  board  made  up 
with  a  few  brads  to  hold  the  ring  compressed,  as 
indicated  in  Figure  43,  is  efficacious. 

New  rings  will  be  so  large  as  to  diameter^ 
that  when  compressed,  fully  closing  the  gap,  they 
either  will  not  fit  into  the  cylinder'  bore  at  all, 
or  else  when 


Fisj.  42.  Trimming  board  and  method 
of  using  it  to  secure  proper  ring  fit  in 
groove. 


HG.43 


they  do  enter 
it  they  will 
not  leave  a 
proper  joint 
clearance.The 

fit     of     the 

rings  to  the 
cylinder  bore  can  be  determined  (Fig.  44)  by 
putting  a  piston  without  rings  and  from  which 
the  piston  pin  and  connecting  rod  have  been 
detached  into  the  cylinder  bore  and  pushing  it 


Fig    43. 

ring" 


Filing  board  for  close  fitting  of 


Major  Engine  Parts. 


59 


far  enough  into  the  cylinder  to  leave  room  be- 
neath it  for  a  piston  ring.  The  ring  should  be 
sprung  into  this  space,  if  possible,  and  the  gap 
clearance  measured  with  a  feeler  gauge.  . 

The  clearance  should  be  just  about  .005  of  'an 
inch.  If  too  small,  hold  the  ring  between  blocks 
of  soft  wood  in  a  vise,  so  as  not  to  mar  the 
edges,  and  file  off  enough  of  the  metal  on  the 
ends  of  the  rings  to  leave  this  clear- 
ance, using  a  very  fine  mill-cut  file 
for  this  work.  If  a  feeler  gauge  is 
not  at  hand,  it  is  well  to 
remember  that  the  thick- 
ness of  a  piece  of 
ordinary  newspaper 
is  .003  of  an  inch, 
so  that  if  a  double  thick- 
ness is  used  to  determine 
the  clearance  the  result 
will  be  entirely  satisfac- 
t  o  r  y.  Naturally,  the 
rings  should  be  fitted  to 
the  cylinders  they  are  to 
work  in;  not  all  to  the 
same  cylinder. 

Care  must  be  taken 
not  to  break  the  rings  in 
placing  them  back  on  the 
pistons.  The  bottom 
ring  should  be  put  on 
first,  using  the  four  little 
metal  strips  to  bridge  the  upper  ring  slots  and 
facilitate  the  manipulation  of  the  ring.  After  the 
rings  are  placed  on  the  piston,  try  them  again  to 
make  sure  that  they  work  freely,  as  a  tight  ring 
may  cause  a  scored  cylinder;  and  even  if  that  is 
escaped,  it  is  bound  to  leak  and  forestall  our 
purpose  in  placing  it  on  the  piston.  Finally,  slip 


Fig.  44.  Method-  of  de- 
termining correct  piston  ring 
gap  clearance. 


60  Tractor  Engines. 

the  rings  around  so  that  the  slots  or  joints  do 
not  fall  in  line;  it  is  well,  before  replacing  the 
pistons  in  the  cylinders,  to  space  the  joints  at  an 
angle  of  120  degrees  with  each  other.  This  will 
tend  to  check. leakage. 

After  new  rings  have  been  fitted,  it  will  take 
a  run  of  at  least  several  hours  for  them  to  have 
worked  into  a  perfect  fit  to  the  cylinder  walls, 
and  it  is  well  to  see  to  it  that  the  engine  has 
plenty  of  oil  during  this  period.  At  the  end  of 
that  time  the  compression  of  the  engine  should 
have  improved  considerably. 

The  connecting  rod  (Figure  45)  in  all  modern 
tractors  is  a  very  substantial  drop  forging,  made 
usually  of  vanadium  steel  or  alloy  steel  of  one 
sort  or  another,  which  is  adapted  to  provide  the 

greatest  degree 
of  toughness 
under  the  work 
encountered.  It 
must  be  re- 
membered that 

sembTed45"  Typkal  connecting  rod  disas-  the    connecting 

rod,     like    the 

wrist  pin,  carries  the  full 'brunt  of  the  explosion, 
and  that,  moreover,  it  is  subjected  to  a  whipping 
action  and  to  pressure  at  an  angle  which  taxes 
its  strength  to  the  utmost. 

It  is  obviously  necessary  to  provide  the  great- 
est degree  of  strength  with  the  least  possible 
weight,  and  in  order  to  accomplish  this  purpose, 
not  only  has  the  engineer  gone  to  the  best  of 
material,  but  he  also  has  gone  to  the  best  pos- 
sible sectional  shape  to  provide  rigidity — the  I-- 
beam. The  rod  as  at  present  designed,  is  in 
reality  an  I-beam  girder,  tapering  from  top  to 
bottom,  and  provided  with  a  split  bearing  holder 


FIG. 45 


n 

HiQ 


Major  Engine  Parts. 


61 


at  the  lower  end,  the  cap  being  bolted  to  the  rod 
proper  by  either  two  or  four  special  steel  bolts. 
It  has  been  usual  in  tractor  practice  to  line  the 
big  end  or 
c  r  a  n  k  p  i  n 
bearing  with 
babbitt  metal, 
which  is 

OU  red,   *  ^  t,0 

the  rod  while 


Fig.  46.     Jig  for  babbitting  connecting  rod. 


molten  and  with  a  mandrel  of  substantially  the 
same  diameter  as  the  crankpin  in  place.  A  jig 
for  pouring  such  a  bearing  is  indicated  in  Fig.  46. 
When  the  metal  has  cooled, 
the  mandrel  is  removed,  the 
rough  parts  of  the  casting 
smoothed  out  and  the  bearing 
split  with  a  saw  along  the 
plane  of  the  bearing  cap  face. 
Then  the  bearing  surface  is 
fi  n  i  s  h  e  d  perfectly,  first  by 
reaming  and  afterward  by 
blueing  and  scraping  to  a  per- 
fect finish. 

Babbitt  metal  is  used  for 
the  bearing  surfaces  in  both 
main  bearings  and  connecting 
rod  bearings,  first,  because  it 
stands  up  well  under  the  fric- 
tion and  the  constant  pound- 
ing due  to  the  explosions  ;  and 
Fig.  47.  Typical  secOnd,  because  it  provides  a 
measure  of  safety.  If,  for 
instance,  the  bearing  should 
become  hot,  due  to  lack  of  oil  or  some  other  cause, 
instead  of  expanding  and  seizing  the  bearing  pin 
as  a  bronze  bearing  would  do,  and  cutting  the 
pin  surface  badly,  and  at  the  same  time  severely 


FfG.47 


piston  and  connecting 
rod  assembly  for 
tractor. 


62 


Tractor  Engines. 


Fig.   48.      Detail  of  piston,  piston  pin  and  connecting  rod  of 
Aultman-Taylor  tractor. 

straining  the  shaft,  the  babbitt  bearing  simply 
melts  and  runs  out,  leaving  the  bearing 'perfectly 
free.  It  immediately  begins  to  give  audible  evi- 
dence in  the  shape  of  a  heavy  pound,  that  some- 
thing is  wrong,  and  the  operator  is  warned  of  the 
necessity  of  shutting  down  the  engine  and  mak- 
ing the  necessary  repairs.  In  the  case  of  the 
bronze  bearing  under  similar  circumstances,  the 
pin  would  be  so  badly  damaged  that  even  if  the 
shaft  were  not  sprung  by  the  severe  strain  im- 
posed by  the  seizure,  regrinding  of  the  pin  to 
bring  it  back  to  a  perfectly  smooth  bearing  sur- 
face would  be  neces- 
sary; that,  of  course, 
entails  removal  of  the 
crankshaft. 

As  might  be  ex- 
pected the  crank- 
shaft as  the  mem- 
ber which  carries  the  full  load  developed  by 
each  of  the  cylinders,  is  made  of  drop-forged 
steel  of  special  analysis  for  toughness ;  generally 
chrome  nickel  steel,  which  resists  crystallization 
well,  or  vanadium  steel,  which  also  presents  a 


»  PfG.4? 


Fig.    49.      Piston   and    connect- 
ing rod  of  Rumely  tractor. 


Major  Engine  Parts. 


63 


Fig.     50.      Three-bearing     crankshaft 
four-cylinder  engine. 


measure  of  protection  from  this  score,  is  em- 
ployed. After  being  roughly  forged,  the  shaft 
is  trimmed  down  to  approximate  shape  and  the 
pins  for  both  main  and  crankpin  bearings  either 

machined  to  a 
finish  or,  as  in 
latter  day  prac- 
t  i  c  e  ,  ground 
for  to  a  perfect 
surface.  The 
number  of  bearings  used  will,  of  course,  depend 
entirely  on  the  type  of  engine  employed,  the 
number  of  .cylinders  used,  etc.,  as  was  made  per- 
fectly plain  in  the  preceding  chapter.  The  bear- 
ings themselves  are  practically  the  same  as  the 
crankpin  bearings,  being  split  with  a  bolted-on 
cap  and  lined  with  babbitt  metal. 

In  realization  that,  after  all,  pouring  a  bearing 
is  not  a  job  to  be  undertaken  by  the  layman — 
especially  when  it  comes  to  fitting — many  tractor 
engine  manufacturers  are  giving  up  the  poured 
babbitt  bearing  in  favor  of  the  shell  type  of  bear- 
ing. Here  we  have  a  bronze  shell  of  exactly 
proper  diameter  to  fit  the  bearing  holder;  this 
bronze  shell  does  not  take  the  wear,  but  simply 
serves  as  a  support  for  the  babbitt  wearing  sur- 
face with  which  it  in  turn  is  lined  ancl  which 
provides  the  ac- 
tual bearing  sur- 
face. The  bronze 
shell  is  riveted, 
or  screwed,solid- 
ly  in  place  in  the 
bearing  holder, 
the  rivet  or  screw  heads  being  countersunk  be- 
low the  bearing  surface  so  that  there  is  no  chance 
of  their  coming  in  contact  with  the  pin  surface. 


Fig.    51.      Two-bearing   crankshaft   on 
Avery  four-cylinder  opposed  engine. 


64 


Tractor  Engines. 


With  this  type  of  bearing,  replacement  of  the 
bearing  is  greatly  facilitated,  for  it  is  simply 
necessary  to  remove  and  discard  the  worn  shell 
and  fasten  the  new  one  firmly  in  place.  Since 

the  shells  are 
made  on  the 
limit  system, 
the  shells  fit 
properly  in 

Fig.  52.  Counterbalanced  crankshaft  on  place  and  fit- 
two-cylinder  vertical  engine.  .  ,  « 

ting  is  reduced 

to  a  minimum.  It  will  even  be  found  that  the 
actual  fitting  of  the  bearing  by  blueing  and  scrap- 
ing after  the  shells  have  been  put  in  place,  is 
reduced  to  a  minimum,  and  we  not  only  get  a 
better  fitting  bearing  when  all  the  work  is  done, 
but  we  also  accomplish  the  work  in  a  very  short 
space  of  time. 

At  one  end,  the  crankshaft  is  provided  with 
a  spur  gear,  which  ,is  sometimes  formed  integral 
with  the  shaft  and  in  other  cases  is  formed  sep- 
arate and  keyed,  pinned  or  otherwise  firmly 
fastened  in  place.  This  gear  meshes  with  a 
second  gear  twice  its 
size,  also  fastened 
firmly  to  the  cam- 
shaf  t,the  two  compris- 
ing the  timing  gear 
train;  the  relation  is 
such  that  the  cam- 
shaft revolves  at  half 
the  crankshaft  speed 
for  the  proper  opera- 
tion of  the  valves,  as 
indicated  in  the  first 
chapter. 

The    Camshaft,     like  Fig.     53.       Rumely    crank 

,    <  1     1       r,         •  case     construction     showing 

the     crankshaft,     is        main  bearings. 


Major  Engine  Parts. 


65 


drop-forged  of  alloy  steel,  and  the  cams  are 
ground  to  exactly  the  proper  contour,  at  the 
same  time  the  bearing  pins  are  trued  up  and 
ground  to  a  proper  finish.  Generally,  consid- 
ering a  four-cylinder  vertical  engine,  the  cam- 
shaft will  be  supported  in  three  bearings,  two  of 
which  will  be  of  greater  diameter  than  the  maxi- 
mum lift  of  the  cams,  so  that  the  bearing,  which 
is  not  split  as  with  the  mainshaft  bearings,  can  be 


.  54.     Method  of  testing  the  truth  of  connecting  rod. 


slipped  over  the  cams  into  place.  With  the  third 
bearing  at  the  front  end,  it  is  not  necessary  to 
provide  such  a  large  diameter,  since  the  shell  need 
not  be  slipped  over  the  cams.  These  bearing 
shells  are  generally  of  bronze. 

Repairs  to  Connecting  Rods,  Etc. — When  mak- 
ing a  general  overhaul  of  the  engine,  it  is  well 
to  check  up  on  the  alignment  of  the  connecting' 
rods,  especially  if  the  engine  has  been  productive 


66 


Tractor  Engines. 


of  an  elusive  knock.  The  rod  may  be  sprung 
so  that  the  piston  is  crowded  at  an  angle  with 
the  cylinder  bore,  or  it  may  be  twisted  so  that 
the  piston  pin  does  not  lie  in  the  same  plane  as 
the  crankpin.  The  proper  method  of  testing  the 
rod  for  these  defects  is  indicated  in  Figure  54. 
A  mandrel  of  the  same  size  as  the  crankpin  is 
supported  in  a  vise  and  the  rod  is  clamped  tightly 
to  this  by  means  of  the  crankpin  bearing.  A  sec- 
ond mandrel  of  a  diameter  the  same  as  the  piston 
pin  is  clamped  in  place  in  the  eye  at  the  upper 
end  of  the  connecting  rod.  These  mandrels 
should  be  sufficiently  long  for  their  parallelism 
to  be  tested.  The  illustration  shows  an  easily 
made  and  convenient  gauge  for  testing  their  pa- 
rallelism. By  sighting  along  the  mandrels  it  is 
easy  to  determine  whether  there  is  a  twist  in  the 
rod,  so  that  the  mandrels  do  not  lie  in  the  same 
plane.  If  either  test  shows  the  rod  to  be  out 
of  truth,  it  can  readily  be  sprung  back  by  bend- 
ing cold,  simply  by  applying  pressure  in  the 
proper  direction  on  the  mandrel  through  the  con- 
necting rod  eye. 

Piston  Pin. 
—The   piston 

pin  itself  will 

give  evidence 

of  wear  after 

long    usage 

and  looseness 

in    the    bush- 
ings provided 

for  it  in  the 

piston   bosses 

will  give  rise 

to   a   sharp 

metallic     click  Fig.    SS.     Removing   piston    and    rod 

i          T  assembly    through    inspection    opening 

Or  knOCK.      in          On  Best  engine. 


Major  Engine  Parts.  67 

such  a  case,  it  will  be  necessary  to  replace  the 
piston  pin  with  a  new  one,  and  in  some  cases 
to  rebush  the  cylinder  bosses.  Try  the  new  pin 
in  the  bosses,  and  if  it  is  a  good,  snug  fit  with 
no  play,  rebushing  will  not  be  required.  If,  how- 
ever, it  is  loose,  the  old  bushings  can  either  be 
reamed  out  to  take  an  oversize  pin  which  is  a 
comparative  simple  operation,  or  they  can  be 
drifted  out  with  a  drift  slightly  smaller  in  diam- 
eter than  the  outside  measurement  of  the  bush- 
ing, care  being  taken  "to  hold  the  piston  firmly 
on  a  soft  wood  saddle  while  the  bushing  is  being 


Fig.  56.  Lower  crank  case  removed,  showing  main  bearings, 
connecting  'rod  and  bearing,  and  the  ease  with  which  piston  is 
removed  in  Waukesha  engine. 

driven  out.  The  new  bushings  can  be  pressed 
into  place  by  means  of  a  press  or  a  vise,  care  be- 
ing taken  to  pad  the  jaws  of  the  press  with  a  soft 
wood  block  so  as  to  mar  neither  the  piston  nor  the 
bushing.  It  will  be  necessary  to  ream  the  new 
bushings  to  take  the  new  piston  pin,  even  though 
it  is  not  oversize.  Extreme  care  should  be  taken 
to  clamp  the  pin  firmly  in  the  eye  of  the  connect- 
ing rod  so  as  to  guard  against  its  working  loose 
and  scoring  the  cylinder  walls. 


68 


Tractor  Engines. 


Where  the  pin  is  locked  in  the  bosses  and  bears 
in  the  rod  eye,  only  one  bushing  at  this  point  is 
necessary. 

Mainshaft  and  Crank  pin  Bearings. — Both  the 
mainshaft  and  crankpih  bearings  are  adjustable. 
Evidence  of  looseness  comes  in  the  form  of  a 
heavy  pound  or  knock,  which  should  be  heeded 
and  the  engine  stopped  immediately.  In  case  a 
crankpin  bearing  is  suspected  of  being  at  fault, 
drain  the  oil  from  the  engine  and  remove  the 
plate  from  the  bottom  of  the  crankcase,  which 

will  expose  the 
connecting  rods 
in  the  case  of. 
a  vertical  cyl- 
i  n  d  e  r  engine 
(Figure  56). 
Sometimes  the 
rods  can  .be 
reached 
through  in- 
spection plates 
in  the  crank- 
case.  Taking 
a  firm  hold  on 
the  crankpin 
bearing  each 
rod  can  be 
tested  in  turn  for  looseness.  In  case  appreciable 
play  is  detected,  take  off  the  crankpin  bearing 
cap,  hold  it  in  a  vise  and  draw  file  the  ends 
(Fig.  57),  taking  very  little  metal  off  and  mak- 
ing sure  to  take  it  off  evenly  all  around  and  just 
as  much  from  one  side  as  from  the  other. 

Where  the  bearing  is  "shimmed"  for  adjust- 
ment (Figure  58),  removal  of  a  thin  shim  on 
either  side  will  •generally  suffice,  no  filing  being 
necessary. 


Fig.   57.      Method  of  adjusting  bearing 
by  filing   off  cap  slightly. 


Major  Engine  Parts. 


69 


Replace  the  cap,  being  sure  that  the  punch 
marks  correspond,  and  tighten  up  the  crankpin 
bearing  bolts  until  the  bearings  fit  the  pin  snugly. 
Test  the  tightness  of  the  bearing  by  turning 

the  engine  over 
with  the  start- 
ing handle. 

In  the  ordi- 
nary course  of 
events,  provided 
the  engine  has 
received  decent 

Fig.   58.     Shimmed  bearing.  j 

treatment  and 

care,  especially  as  to  correct  lubrication,  it  will 
be  necessary  to  take  up  on  all  the  crankpin  bear- 
ings slightly  once  every  couple  of  months.  Pro- 
ceed as  above,  being  careful  not  to  get  the  bear- 
ings too  tight,  as  in  that  case  they  will  cut  out 
rapidly.  After  adjusting  the  bearings,  it  is  well 
to  idle  the  engine  for  a  couple  of  hours  before 
taking  the  tractor  into  the  field  to  run  the  bear- 
ings in  to  a  good  fit.  Do  not  forget  to  lock  the 
crankpin  bearing  bolt  nuts  when  the  bearings 
have  been  properly  fitted  and  set  up. 


Fig.    59.      Rough   spotting   to   determine  where   bearing   surface 
is  high. 


70  Tractor  Engines. 

In  case  the  wear  is  too  great  to  be  taken  up 
by  the  above  method,  or  in  case  of  bearing  fail- 
ure, the  rod  will  have  to  be  rebabbbitted.  To  do 
a  worth  while  job  of  repouring  a  bearing  requires 
,not  only  proper  equipment  in  the  way  of  a  jig, 
but  also  experience  in  bearing  pouring.  The 
best  advice  that  can  be  given  in  a  case  of  -this 
sort,  is  to  send  the  rod  or  rods  off  to  the  nearest 
service  station  or  the  nearest  competent  repair- 
man, who  will  rebabbitt  the  bearing  at  small  cost. 

With  the  rod  relined  with  new  babbitt,  it  is 


Fig.    60.     Illustrating    correct    method    of    scraping    a    bearing 
after  "spotting"  to  determine  the  high  spots. 

not  a  difficult  job  for  the  man  with  patience  and  a 
limited  amount  of  mechanical  skill  to  spot  and 
scrape  in  the  bearing  to  a  good  fit  on  the  crank- 
pin.  Coat  the  surface  of  the  crankpin  with  a 
very  thin  film  of  Prussian  blue;  the  thinner  the 
better,  and  it  should  be  spread  perfectly  even. 
After  thoroughly  coating  the  pin,  mount  the 
bearing  on  it,  clamping  it  firmly,  but  not  so 
tightly  in  place  that  it  cannot  be  turned ;  be  sure 
and  apply  it  to  the  pin  in  the  same  position  as 


Major  Engine  Parts.  71 

it  will  be  used  in  the  engine  when  reassembled 
(Fig.  59).  Then  turn  the  bearing  around  a  couple 
of  times,  undo  the  bolts  and  remove  it.  It  will 
be  found  that  all  the  high  spots  on  the  bearing 
surface  will  show  up  in  blue  both  on  the  upper 
half  and  the  lower  half.  'Now  hold  the  bearing 
in  the  vise,  as  shown  in  Fig.  60,  and  with  a  good, 
sharp  bearing  scraper  scrape  a  small  amount  of 
metal  off  these  high  spots,  and  in  fact  from  the 
area  just  around  them.  When  both  top  and  cap 
have  been  scraped,  reclamp  bearing  on  the  pin 
after  spreading  out.  the  blue  again,  and  take 
another  impression.  If  the  scraping  has  been 
carefully  done,  the  blue  this  time  will  cover  a 
much  larger  surface. 

Scrape  down  the  high  spots  again,  being  more 
careful  to  take  only  a  small  amount  of  metal  off.- 
Use  the  flat  of  the  scraper  blade  and  give  it  a 
twisting  diagonal  stroke  in  order  to  avoid  ridg- 
ing the  comparatively  soft  bearing  metal.  After 
several  repetitions  of  this  process,  the  blued  area 
will  be  found  to  very  nearly  cover  the  bearing 
surface,  provided  the  scraping  has  been  discreetly 
done.  Then  wipe  bearing  and  pin  clean,  smear 
it  well  with  lubricating  oil  and  adjust  it  to  a  snug 
fit  as  indicated  above.  If  it  is  found,  when  it 
comes  time  to  set  up  the  bearing,  that  when  the 
bolts  are  screwed  up  tight  the  bearing  grips  the 
pin  too  tightly,  cut  several  shims  of  very  thin 
brass — .002  to  .004  of  an  inch — and  place  an 
equal  number  of  these  on  each  side  of  the  bear- 
ing between  the  two  halves  to  provide  a  correct 
adjustment  when  the  bearing  bolt  screws  are 
pulled  up  tight. 

In  every  case  when  it  is  found  necessary  to 
reline  a  bearing,  the  pin  should  be  carefully 
examined  for  roughness  or  ridges ;  it  is  well 
also  to  test  it  for  roundness  with  a  micrometer 


72  Tractor  Engines. 

or  a  good  pair  of  calipers  if  these  instruments 
are  at  hand.  If  the  pin  is  at  all  rough,  do  not 
attempt  to  fit  a  new  bearing  on  it  until  it  has 
been  smoothed  up  and  put  in  good  condition 
again.  If  this  precaution  is  not  observed,  all  the 
trouble  and  expense  of  putting  in  the  new  bear- 
ing will  come  to  naught,  for  it  will  quickly  be 
cut  out  again,  making  a  repetition  of  the  task 
necessary.  An  experienced  machinist  can  take 
a  pin  that  is  not  too  badly  scored  and  file  it  to 
approximate  condition,  finishing  it  off  by  lapping 
with  a  clamp  and  very  fine  abrasive.  The  best 
plan,  however,  is  to  send  the  crankshaft  that  is 
found  to  be  scored  as  to  the  bearing  pins  to  the 
service  station  and  have  it  reground  and  put  in 
first-class  shape  again. 

In  connection  with  the  above,  one  of  the  lead- 
ing tractor  manufacturers  says: 

"Fitting  connecting  rod  bearings  is  very  im- 
portant, and  you  should  know  that  the  rods  fit 
properly  at  all  times.  Do  not  allow  them  to  run 
loose  and  'pound/  It  is  important  to  keep  con- 
necting rods  tight  and  well-oiled  at  all  times. 
Bearings  are  constructed  so  that  shims  can  be 
removed  to  take  up  the  wear.  When  bearings 
are  worn  so  badly  that  all  shims  have  been  re- 
moved it  is  then  necessary  to  use  new  bearings. 

"The  one-half  bearing  grooved  for  oil  must  be 
fitted  in  lower  one-half  of  connecting  rod  shell. 

"The  first  operation  is  to  fit  the  shells  tight  in 
the  connecting  rod  and  the  connecting  rod  cap 
so  they  will  have  a  full  bearing  back  of  the  shell. 
About  the  best  way  to  get  a  good  fit  is  to  place 
the  shell  on  the  crankshaft  and  then  tap  the  cap 
to  place,  as  shown  in  Fig.  61. 

"The  next  operation  is  to  get  a  good  bearing 
fit  to  the  crank.  To  do  this,  it  is  best  to  use 
lamp  black  to  'paint'  the  pin  or  crankshaft,  then 


Major  Engine  Parts. 


73 


set  half  of  bearing  on  pin  and  work  back  and 
forth ;  the  lamp  black  will  show  the  high  places 
or  where  bearing  needs  to  be  scraped.  Keep  this 
operation  up  until  the  bearings  show  a  nice  even 
fit  all  over  the  surface  before  you  put  the  rods 
on  the  crankshaft  to  stay. 

"The  connecting  rod  bolts  should  be  drawn  up 
tight,  when  the  bearings  are  properly  fitted  and 
bolts  drawn  up  as  tightly  as  possible,  the  connect- 
ing rod  bearings  should  almost  sustain  the  weight 


Fig.  61.     Fitting  bearing  shell  to  rod  bearing. 

of  the  rod.  If  the  cylinder  is  off  and  the  rod 
raised  to  the'  top  it  should  just  'ease'  down  of 
its  own  weight.  If  it  drops  easily  and  loosely 
it  has  not  been  fitted  close  enough.  If  the  cylin- 
der is  not  off,  test  it  by  turning  fly-wheel. 

"If  the  rod  will  not  fall  of  its  own  weight,  not 
enough  shims  have  been  used.  Do  not  back  the 
nut  off  until  the  rod  will  drop,  but  put  in  more 


74 


Tractor  Engines. 


shims.  The  bolts  should  be  tight,  and  edges  of 
bearings  should  be  in  close  contact  with  shims. 
It  pays  to  fit  the  bearings  properly. 

"Every  morning  take  off  inspection  plate  and 
examine  the  bearings  and  oil  level,  and  see  that 
the  connecting  rod  bolts  are  tight.  Remember 
the  old  adage,  'A  stitch  in  time  saves  nine.'  It 
is  mighty  true  with  a  motor.  A  little  neglect  may 
cause  an  expensive  break." 

To  take  up  on  the  mainshaft  bearings,  take  off 
the  three  babbitted  caps  from  the  mainshaft  bear- 
ings and  clean  the  bearing  surface  with  gasoline. 

Apply  Prussian  blue  or  red  lead  to  the  crank- 
shaft bearing  surfaces,  which  will  enable  you,  in 
fitting  the  caps,  to  determine  whether  a  perfect 
bearing  surface  is  obtained. 

Place  the  rear  cap  in  position  and  tighten  it  up 
as  much  as  possible  without  stripping  the  bolt 
threads.  When  the  bearing  has  been  properly 
fitted,  the  crankshaft  will  permit  moving  with 
one  hand..  If  the 
crankshaft  cannot  be 
turned  with  m  one 
hand,  the  contact 
between  the  bearing 
surfaces  is  evidently 
too  close,  and  the 'cap 
requires  shimming  up, 
one  or 'two  brass  lin- 
ers usually  being  suf- 
ficient. In  case  the 
crankshaft  moves  too 
easily  with  one  hand, 
the  shims  should  be 
removed  and  the  steel 
surface  of  the  cap 
filed  off,  permitting 
it  to  set  closer. 


Fig.  62.  Showing  simple 
means  of  adjusting  Avery 
mainshaft  bearings. 


Major  Engine  Parts.  75 

After  removing  the  cap,  observe  whether  the 
blue  or  red  "spottings"  indicate  a  full  bearing 
the  length  of  the  cap.  If  "spottings"  do  not 
show  a  true  bearing,  the  babbitt  should  be  scraped 
and  the  cap  refitted  until  the  proper  results  are 
obtained. 

Lay  the  rear  cap  aside  and  proceed  to  adjust 
the  center  bearing  in  the  same  manner.  Repeat 
the  operation  with  the  front  bearing,  with  the 
other  two  bearings  laid  aside. 

When  the  proper  adjustment  of  each  bearing 
has  been  obtained,  clean  the  babbitt  surface  care- 
fully and  place  a  little  lubricating  oil  on  the  bear- 
ings, also  on  the  crankshaft;  then  draw  the  caps 
up  as  closely  as  possible — the  necessary  shims, 
of  course,  being  in  place.  Do  not  be  afraid  of 
getting  the  cap  bolts  too  tight,  as  the  shim  under 
the  cap  and  the  oil  between  the  bearing  surfaces 
will  prevent  the  metal  being  drawn  into  too  close 
contact.  If  oil  is  not  put  on  the  bearing  surfaces, 
the  babbitt  is  apt  to  cut  out  when  the  motor  is 
started  up  before  the  oil  in  the  crankcase  can  get 
into  the  bearing. 

It  must  be  remembered  that  after  scraping,  the 
bearings  will  not  be  a  snug  fit  on  the  pins,  but 
will  touch  only  at  the  high  spots ;  if  the  scraping 
has  been  carefully  done  these  high  spots  will  be 
very  numerous,  spread  all  over  the  bearing  sur- 
faces, and  naturally  be  comparatively  small. 
After  the  bearing  has  been  run  in  for  a  couple  of 
hours,  provided  it  is  given  plenty  of  oil,  it  should 
wear  down  "to  a  perfect  fit  on  the  pin,  which 
should  eliminate  arty  tendency  for  it  to  bind. 

After  long  use,  especially  if  the  crankcase  oil 
has  not  been  changed  at  frequent  intervals,  the 
bearing  surface  will  contain  embedded  gritty 
matter  which  will  act  as  an  abrasive  and  lap  the 
bearing  pin  somewhat.  In  order  to  correct  this 


76  Tractor  Engines. 

condition,  it  will  be  necessary  to  scrape  the  sur- 
face of  the  bearings,  spot  them  in  and  refit  them 
to  proper  alignment. 

Crankshaft. — Aside  from  truing  up  the  bear- 
ing pins  as  outlined  under  the  last  heading,  the 
only  repair  that  is  ever  called  for  by  the  crank- 
shaft is  to  test  it  out  for  true  running  between 
centers  or  on  knife  edgesi  If  it  is  found  to  be 
sprung,  unless  the  spring  is  comparatively  slight 
it  should  be  discarded  and  replaced  with  a  new 
shaft.  A  slight  spring  can  be  taken  out,  but  as 
special  jigs  are  necessary,  the  shaft  should  be 
returned  to  the  factory  or  to  the  nearest  service 
station  for  this  treatment. 

Camshaft. — Repairs  to  the  camshaft  are  in- 
frequent, since  it  is  not  subjected  to  hard  wear. 
After  several  seasons'  use,  sufficient  looseness 
may  be  detected  in  the  camshaft  bearings  to 
make  rebushing  desirable;  this  is  a  simple  mat- 
ter of  drifting  out  the  old  bushings  and  pressing' 
in  new  ones,  much  as  the  piston  pin  bushings  in 
the  piston  bosses  were  refitted.  It  sometimes 
happens  also  that  the  camshaft  becomes  sprung, 
generally  as  a  result  of  being  hit  with  a  broken 
connecting  rod  or  some  similar  mishap.  If  not 
too  badly  sprung,  this  fault  can  be  corrected  by 
blocking  the  shaft  between  two  wooden  'blocks 
and  applying  pressure  with  a  lever  or  jack  at  the 
high  point  to  bring  it  back  to  shape;  if  badly 
sprung,  and  especially  if  the  cams  show  appre- 
ciable wear,  it  is  a  better  plan  to  replace  the  cam- 
shaft with  a  new  one. 

Tools  and  Their  Use. — To  properly  care  for 
a  piece  of  machinery,  certain  tools  are  necessary 
in  order  to  do  the  job  quickly  and  correctly. 

One  of  the  chief  causes  of  serious  tractor 
troubles  is  that  the  adjusting  or  repairing  is  not 


Major  Engine  Parts. 


77 


done  when  it  should  be  done,  and  very  often  on 
account  of  the  lack  of  proper  tools  or  not  know- 
ing what  tools  to  have  on  hand. 


\&**&**          m 

"tj    YfS£. 

•     -   O 


Fig.  63.      Useful  tools  for  tractor  operators. 

The  following  list  of  tools  will  be  found  about 
all  that  are  necessary  for  doing  all  kinds  of  ad- 
justing and  repairing  on  your  tractor,  and  from 


78  Tractor  Engines. 

time  to  time  one  will  get  other  handy  and  useful 
tools: 

One  1^2 -pound  ball  pene  hammer. 

One  screwdriver,  10-inch. 

Two  24-inch  flat  cold  chisels,  and 

One- fourth  round  nose  chisel. 

Two  oil  groove  chisels. 

No.  41  S  wrench  (semi-finish). 

No.  37  S  wrench  (semi-finish). 

8-inch  crescent  wrench. 
12-inch  monkey  wrench. 
18-inch  pipe  wrench. 

Two  round  punches,  j^-inch  and  %-inch. 
Hack  saw  frame  and  10-inch  blades. 
Pair  tinner's  snips. 
Carpenters'  bit  brace. 
Flat  files,  such  as  10  and  14-inch. 
Half-round  file  (14-inch). 
Round  file   (^-inch). 
Combination  square  with  18-inch  blade. 
Pair  of  good  pliers. 
A  carpenters'  pinch-bar. 
One  10-inch  and  14-inch  babbitt  scraper. 
Two  pieces  of  ^-inch  square  hemp  packing, 

18  inches  long. 
Two  spring  clamp  rings. 
Carborundum   stone. 
Soldering'  iron  and  solder. 
A  whisk  broom. 
A  good  bench  vise. 

The  oil  groove  chisels  are  for  cutting  oil 
grooves  in  bearings,  and  you  should  own  two  of 
them,  one  with  about  y&"  cutting  edge  and  3-16" 
on  the  other,  so  that  grooves  can  be  cut  proper 
size  in  both  large  and  small  bearings. 

The  No.  41  S  wrench  fits  standard  size  nuts 
of  ft"  and  1",  and  the  No.  37  fits  $/&"  and 


Major  Engine  Parts.  79 

24"  nuts,  these  four  sizes  being  standard,  and 
you  will  find  most  of  the  bolts  and  nuts  on  your 
tractor  about  that  size.  The  8"  crescent  wrench 
will  take  all  sizes  from  y%"  down  as  well  as 
cap  screws.  The  18"  pipe  wrench  is  about  right, 
since  it  will  take  all  sizes  of  pipe  used  on  your 
tractor. 

The  hack  saw  is  a  very  handy  tool  when  doing 
all  kinds  of  repair  work  where  a  saw  can  be  used. 

A  pair  of  tinner's  snips  are  necessary  when 
making  new  shims  for  bearings,  etc. 

Flat  files  can  be  purchased  in  all  sizes  to  suit 
the  needs.  A  half-round  and  a.  round  file  will 
be  found  very  useful  when  enlarging  bolt  holes, 
etc.,  about  implements. 

The  combination  square  with  18-inch  blade 
will  be  found  very  handy  when  lining  and  squar- 
ing up  bearings  for  babbitting,  etc. 

A  short  carpenter's  pinch-bar  will  be  used  very 
much  around  the  farm  and  on  the  outfit. 

When  babbitting  bearings  the  most  important 
tools  for  such  work  are  your  babbitt  scrapers. 
A  set  of  good  scrapers  can  be  made  out  of  a 
10-inch  and  a  14-inch  half-round  file  by  grinding 
off  all  the  teeth  on  an  emery  wheel  and  then 
finish  up  smooth  on  a  grindstone.  Be  careful 
when  grinding  on  emery  wheel  so  as  not  to  draw 
the  temper  out  of  edge  of  file  by  allowing  to  get 
too  hot.  Continually  dip  file  in  water  to  keep 
it  cool  while  grinding.  The  flat  side  should  be 
ground  out  hollow,  since  in  such  shape  it  will 
sharpen  easily  and  quickly. 

The  carborundum  stone  is  for  the  purpose  of 
keeping  the  edges  of  your  scraper  sharp  so  it 
will  cut  babbitt.  You  will  find  that  a  sharp 
scraper  will  cut  babbitt  and  also  brass  very  easily. 


80  Tractor  Engines. 

When  dull  it  is  almost  impossible  to  touch  it  by 
scraping.  You  should  make  a  case  for  your 
scraper  out  of  paper,  cloth  or  wood,  so  as  to 
protect  its  edge  when  not  in  use. 

The  two  pieces  of  half -inch  square  hemp  pack- 
ing are  used  to  make  a  tight  joint  around  shafts 
or  hubs  of  gear  when  babbitting,  and  the  spring 
clamp  rings  are  used  to  hold  the  hemp  up  tight 
in  place. 

A  soldering  iron  and  some  solder  are  very 
useful. when  mending  oil  cans,  pipes,  and  such 
parts  as  can  be  repaired  by  soldering.  The  flux 
used  when  soldering  is  commercial  muriatic  acid 
with  as  much  zinc  put  into  it  as  it  will  dissolve, 
and  have  all  surface  to  be  soldered  clean  and 
bright. 

A  whisk  broom  is  one  of  the  handiest  articles 
with  which  to  keep  a  tractor  clean.  It  will  be 
found  that  if  the  operator  will  from  time  to  time 
brush  off  all  the  dirt  and  trash  which  settles  on 
a  tractor  he  will  be  able  to  keep  it  clean  with  a 
very  small  amount  of  time  spent  with  the  whisk 
broom.  For  the  purpose  of  wiping  up  grease 
and  oil,  old  gaudy  sacks  cut  up,  or  cotton  waste 
should  be  used. 

A  bench  vise  attached  to  the  rear  platform  of 
tractor  will  be  found  handy  all  the  time  and 
should  be  one  of  the  tools  first  purchased. 

The  equipment  for  handling  lubricants  for 
tractor  use  are  as  follows : 

The  can  in  which  hard  oil  is  carried  on  the 
tractor  for  all  hard  oil  compression  cups  should 
not  be  larger  than  five  or  ten-pound  capacity, 
and  should  have  a  tight  cover,  one  which  will 
keep  out  all  grit  and  dirt. 

When  taking  out  grease,  to  fill  a  grease  cup, 
use  a  short  paddle  which  can  be  carried  in  the 


Major  Engine  Parts.  81 

grease  can  and  remove  the  grease  from  on  top 
of  grease  in  can.  Do  not  dig  a  hole  in  the  center 
of  the  grease  and  continue  it  to  the  bottom  of 
pail  or  can.  By  digging  out  the  middle  and 
having  such  a  cavity  in  grease,  helps  to  collect 
grit  and  trash  which  may  fall  into  can  unnoticed 
and  thus  get  mixed  with  the  grease,  and  thus 
goes  into  a  bearing,  where  it  does  a  great  amount 
of  harm,  even  more  than  the  operator  believes 
possible.  Keep  grease  clean. 

The  can  in  which  you  carry  gas  engine  cylinder 
oil  should  be  about  two  or  three  gallon  capacity. 
A  five-gallon  can  is  too  clumsy  and  hard  to 
handle.  In  a  short  time  more  oil  will  be  spilled 
than  the  cost  of  two  or  three  smaller  cans.  Keep 
the  can  closed  up  tight  with  a  screw  top  or  corked 
with  a  cork  of  solid  material  such  as  wood  or 
lead.  Never  use  a  corn  cob,  as  it  breaks  up 
easily  and  drops  into  the  oil  can;  from  there  it 
gets  into  the  lubricator  and  stops  it  up,  thus  again 
causing  considerable  delay  and  possibly  damage. 

Keep  your  oiling  equipment  clean.  x  A  small 
funnel  with  a  medium  fine  screen  should  be  used 
when  drawing  oil  from  the  barrel  into  the  can, 
so  as  to  catch  all  chips  from  the  bearings  which 
get  into  a  barrel  when  tapping  for  faucet,  and 
also  can  be  used  when  filling  lubricator  on  trac- 
tor. Keep  the  funnel  clean  so  no  dirt  gets  into 
oil  by  first  lodging  on  funnel. 

The  oil  which  is  taken  out  of  the  splash  basin 
of  your  motor  from  time  to  time  can  be  filtered 
through  a  filter.  Take  a  fifteen  or  twenty-gallon 
can  or  barrel  and  cut  several  small  holes  in  its 
bottom  and  fill  about  half  full  of  cotton  waste 
or  gunny  sacks.  The  oil  is  poured  into  top  of 
can  and  passes  slowly  through  filter  and  is  caught 
in  another  receiver  below  filter.  This  oil  can 


82  Tractor  Engines. 

be   used    for   gear   oil   or   on   other   machinery. 
Never  use  it  in  motor  again. 

Whenever  a  man  visits  a  tractor,  and  he  looks 
inside  of  the  tool-box  and  sees  a  heap  of  scrap 
iron,  broken  bolts,  nuts,  earth  and  tools  mixed 
together,  and  then  glances  at  the  oil-handling 
equipment  and  sees  an  oil  can  wide  open  covered 
with  dirt,  and  grease  can  without  a  cover  and 
jammed  into  all  kinds  of  shapes,  he  will  not  need 
to  look  over  the  tractor  to  tell  just  what  kind  of 
shape  it  is  in.  An  operator  can  be  judged  by  the 
apearance  of  the  oiling  equipment  and  tool-box/ 


CHAPTER  IV. 

Valves  and  Valve  Mechanism. 

How   They   Differ    and   the   Advantages   of    EacK 
Type — Proper   Care    and   Adjustment. 

TAKEN  all  in  all,  there  is  no  system  of  the 
several  which  go  to  make  the  complete 
tractor  engine  that  is  of  more  importance  to  the 
correct  functioning  of  the  motor  than  the  valve 
system.  As  a  matter  of  cold  fact,  it  is  doubtful 
if  there  is  any  other  feature  of  engine  design 
that  has  been  given  as  much  careful  considera- 
tion and  experimental  work  as  has  the  design 
and  the  arrangement  of  the  various  parts  which 
have  to  do  with  the  functioning  of  the  valves. 

We  have  alluded,  in  chapters  ahead,  .to  vari- 
ous valve  arrangements ;  particularly  the  L-head 
and  the  valve-in-head  types.  In  all,  there  are 
five  distinct  valve  arrangements  commonly  em- 
ployed in  internal  combustion  engine  work,  as 
follows :  T-head,  in  which  the  cylinder  is  pro- 
vided with  two  cylinder  pockets  so  that  in  cross 
section  it  resembles  a  Capital  T,  one  valve  being 
located  in  each  of  these  pockets.  Such  a  con- 
struction gives  a  very  accessible  engine ;  however, 
it  entails  the  use  of  two  camshafts,  while  at  the 
same  time  the  presence  of  cylinder  pockets  to 
any  greater  degree  than  is  absolutely  necessary  is 
by  no  means  desirable.  This  is  due  to  the  fact 
that  the  pocket  provides  additional  surface  for 
the  radiation  and  loss  of  the  heat  of  the  explo- 
sion, which,  as  we  learned  in  the  first  chapter,  is 
the  real  source  of  our  power,  and  the  efficiency 
of  the  engine  is  impaired  as  a  consequence.  Also 

(83)    ' 


84  Tractor  Engines. 

the  presence  of  a  pocket,  or  two  pockets,  con- 
siderably retards  the  speed  with  which  full  com- 
bustion of  the  fuel  charge  can  be  effected,  and 
by  so  doing  we  have  a  second  cause  of  power 
loss. 

The  second  type  is  the  L-head  type,  with  both 
valves  positioned  in  a  single  cylinde'r  pocket  and 
operated  from  a  single  camshaft.  This  arrange- 
ment has  the  virtue  of  compactness  and  ex- 
treme simplicity,  as  to  valve  operating  mech- 
anism, and  for  these  reasons  it  is  typical  of 
present-day  tractor  engine  practice.  The  single 
pocket  is  not  a  great  drawback  and  many  manu- 
facturers consider  the  accessibility  and  the  sim- 
plicity which  it  gives  rise  to  of  greater  import- 
ance than  the  slight  power  increase  which  can 
be  attained  by  eliminating  the  pocket  altogether. 

The  third  system,  and  the  one  which  at  the 
present  time  is  making  the  greatest  progress  in 
the  tractor  industry,  is  the  valve-in-head  type, 
in  which  'both  the  valves  are  located  in  the  cylin- 
der head  and  operated  by  means  of  long  push 
rods  and  tilting  levers  or  rocker  arms  from  a  sin- 
gle camshaft.  The  virtue  of  this  system 'is  that 
it  provides  a  combustion  chamber  which  is  a 
very  close  approach  to  the  ideal  spherical  shape ; 
there  are  no  pockets  in  the  cylinder  and  the  com- 
bustion chamber  presents  less  wall  area  for  heat 
radiation  in  proportion  to  capacity  than  with  any 
other  type ;  at  the  same  time,  the  location  of  the 
spark  plug  is  such  that  we  obtain  the  fastest  pos- 
sible speed  of  the  flame — rapid  flame  propaga- 
tion, as  we  term  it — with  no  pocket  of  dead  or 
partially  dead  gas  to  retaAl  it. 

It  has  the  disadvantage  of  introducing  some 
complication  into  the  valve  operating  mechanism ; 
more  parts  to  wear  and  need  adjustment.  But 
in  the  modern  valve-in-head  engine,  these 


Valves  and  Valve  Mechanism.       85 


!*is 

to1 


86  Tractor  Engines. 

little  points  have  been  so  well  worked  out  that 
no  trouble  on  the  score  of  wear  and  lack  of  ad- 
justment are  chargeable  against  the  valve-in- 
head  engine,  provided  it  is  given  at  least  as  good 
treatment  as  any  of  the  other  types. 

The  two  other  types  are  by  no  means  a  factor 
in  the  tractor  industry  and  we  will  dismiss  them 
with  a  word.  They  are  the  F-head  system  with 
a  single  valve — the  inlet — located  in  the  cylinder 
head,  and  the  exhaust  valve  located  in  the  single 
cylinder  pocket ;  and  the  Knight  sleeve  valve 
type,  in  which  the  functions  of  the  valves  are 
performed  by  two  sliding  sleeves  surrounding 
the  piston.  In  the  F-head  type,  we  can  obtain 
very  large  valve  areas  with  a  very  small  cylinder 
pocket,  much  larger  than  can  be  obtained  with 
the  L-head  type,  and  also  much  larger  than  can 
be  obtained  with  the,  valve-in-head  type.  An 
engine  with  this  valve  arrangement,  therefore,  is 
particularly  powerful  despite  the  presence  of  the 
small  valve  pocket ;  however,  the  complication  of 
the  valve  mechanism  has  stood  in  the  way  of  the 
development  of  the  type  for  tractor  service,  al- 
though in  automobile  application  it  is  making 
marked  progress.  The  Knight  engine  is  not 
used  for  tractor  service. 

In  Figure  64  the  assembly  of  the  cylinders,  pis- 
tons, crankshaft,  etc.,  with  the  camshaft  and  the 
valve  mechanism  on  a  typical  four-cylinder  en- 
gine of  the  ve'rtical  L-head  type  indicates  clearly 
the  relation  of  the  various  parts  and  the  func- 
tioning of  each.  The  valve  proper,  which  is 
pictured  in  Figure  65,  is  made  of  tungsten  steel 
in  most  modern  motors,  although  quite  a  few 
manufacturers  employ  a  cast-iron  head  with  a 
ste.el  stem  welded  in  place.  The  cast-iron  stands 
the  heat  well,  which  is  of  great  importance,  es- 
pecially in  the  case  of  the  exhaust  valve,'  which 


Valves  and  Valve  Mechanism.       87 


is  constantly  subjected  to  the  intense  heat  of  the 
exhaust  gases ;  tungsten  steel  has  been  found 
even  more  efficacious  from  the  heat-resisting 
standpoint,  while  at  the  same  time  the  all-steel 
valve  is  not  particularly  subject  to  warping. 

The  valve  head  is  shaped  like  a  manhole  and 
has  a  beveled  edge  which  seats  on  a  similarly 
shaped  seat  formed  in  the  cylinder,  so  that  when 
the  valve  is  closed  no  leakage  can  occur  around 
the  seat  and  through  the  port,  provided  the  valve 
is  in  good  condition.  The  valve  is  ground  to  a 
gas-tight  fit  with  the  cylinder  seat  when  the  en- 
gine is  as- 
sembled at  the 
factory. 

The  valve 
is  positioned, 
with  relation 
to  the  port 
which  it  con- 
,  t  r  o 1  s  ,  by 
means  of  a 
valve  stem 
guide  in 
which  the 
stem  of  the 
valve  finds  a  bearing.  This  guide  is  usually 
formed  of  cast-iron  similar  to  the  cylinder,  and 
in  fact  in  some  instances,  is  formed  integral  with 
the  cylinder  casting.  The  usual  practice,  how- 
ever, is  to  make  the  guide  separate  and  press  it 
into  place,  so  that  when  wear  occurs  the  ill  re- 
sults occasioned  by  it  can  be  remedied  by  remov- 
ing the  worn  guide  and  fitting  a  new  one. 

It  will  be  seen  that  the  cam  does  not  act 
directly  against  the  bottom  of  the  valve  stem;  a 
mushroom-shaped  cam  follower,  push  rod  or 
tappet,  as  it  is  variously  called,  is  interposed 


f  16.65 ' 
W 

Fig.  65.  Showing  the  valve  and  cam  fol- 
lower assembly  and  how  the  cam  follower 
is  actuated  by  the  cam. 


88  Tractor  Engines. 


between  the  cam  and  the  valve  stem  and  it  finds 
its  bearing  in  a  tappet  guide  formed  in  the  shelf 
on  the  upper  half  of  the  crankcase.  These  cam 
followers  are  also  case  hardene4  to  prevent 
rapid  wear. 

The  shape  of  the  valve  tappet  is  not  always 
the  same.  In  some  engines  the  tappet  is  fitted 
with  a  roller  which  bears  on  the  cam  to  reduce 
wear  and  noise. 

The  valve  stem  is  surrounded  by  a  valve 
spring,  helical  in  shape,  which  bears  against  the 
under  side  of  the  valve  pocket  in  the  cylinder, 
being  centered  by  the  valve  stem  guide,  and 
which  is  held  on  the  stem  by  means  of  a  washer 
and  a  short  key  or  pin  passing  through  a  hole  in 
the  lower  end  of  the  valve  stem.  Other  locking 
arrangements,  such  as  horseshoe  washers,  fitting 
into  recesses  on  the  valve  stems,  are  sometimes 
used. 

This  spring  is  sufficiently  strong  to  return  the 
valve  rapidly  to  its  seat  when  the  cam  follower 
rides  off  the  hill  on  the  cam.  It  is  also  suffi- 
ciently strong  to  prevent  the  exhaust  valve  open- 
ing under  the  suction  or  reduced  atmospheric 
pressure  in  the  cylinder  on  the  inlet  stroke. 

Due  to  the  arrangement  of  the  crank  throws 
on  the  crankshaft,  it  is  not  possible  to  fire  the 
cylinders  in  exact  rotation  starting  with  number 
one — which  is  always  the  cylinder  at  the  timing 
gear  end  of  the  engine — and  working  back  in 
numerical  order.  On  the  four-cylinder  engine 
shown  in  Figure  64  the  firing  order  is  1,  2,  4,  3. 
Just  what  is  happening  in  each  of  the  cylinders 
when  -any  particular  one  is  firing  is  made  plain 
by  reading  across  in  the  following  tabulation. 
Reading  down  shows  the  order  of  the  strokes'in 
any  one  cylinder : 


,A~ 


Valves  and  Valve  Mechanism.       89 

Cylinder  No.  1      No.  2  No.  4  No.  3 

Power  Compression  Intake  Exhaust 

Exhaust  Power  Compression  Intake 

Intake  ,  Exhaust  Power  Compression 

Compression   Intake  Exhaust  Power 

In  other  words,  when  cylinder  No.  1  is  firing, 
No.  2  is  on  the  compression  stroke  getting  ready 
to  fire  next.  No.  4  is  on  the  intake  stroke  and 
No.  3,  having  just  fired,  is  exhausting. 

In  Figure  64  cylinder  No.  2  is  shown  on  the 
power  stroke  and  naturally  both  valves  will  be 
closed.  Reference  to  the  tabulation  will  show 
that  No.  1  should  be  on  the  exhaust  stroke  and 
it  will  be  evident  that  the  exhaust  valve  on  No.  1 
cylinder  is  raised  in  the  figure.  No.  3  should  be 
on  the  intake  stroke ;  the  lifted  inlet  valve  in  the 
illustration  proves  the  correctness,  while  No.  4 
should  be  on  the  compression  stroke  with  both 
valves  closed;  it  is  found  to  be  so. 

There  is  one  other  possible  firing  order  on  a 
four-cylinder  engine  with  this  type  of  crank- 
shaft, and,  in  fact,  it  is  the  more  commonly  met 
with.  It  is  1,  3,  4,  2. 

In  the  preceding  chapter  it  was  pointed  out 
that  the  time  of  opening  and  closing  of  the 
valves  was  of  great  importance.  While  in  seek-N^ 
ing  to  obtain  an  insight  into  the  principles  of  the  \ 
engine  it  is  well  to  consider  that  the  valves  open 
and  shut  exactly  on  the  top  and  bottom  dead 
centers,  as  the  case  may  be,  and  remain  open 
exactly  one  piston  'stroke  up  or  down  or  180 
degrees  of  crankshaft  movement;  as  a  matter  of 
fact  in  the  practical  engine  such  is  not  the  case 
by  a  large  margin. 

As  a  rule,  the  inlet  valve  does  open,  or  begin  to 
open,  when  the  piston  is  very  near  the  top  dead 
center  just  starting  down  on  its  intake  stroke. 


90  Tractor  Engines. 


The  downward  travel  of  the  piston  is  completed 
in  a  very  short  space  of  time — a  fraction  of  a 
second — when  the  engine  is  turning  over  at  its 
rated  speed  and  in  order  for  the  new  charge  of 
gas  to  enter  the  cylinder  through  the  inlet  piping 
in  sufficient  quantity  to  fill  the  cylinder,  its 
velocity  through  the  constricted  passages  must, 
be  high. 

It  is  true  that  all  bodies  in  motion  acquire 
momentum — that  is,  a  tendency  to  persist  in 
motion.  The  momentum  is  measured"  by  the 
velocity  at  which  the  body  is  traveling  multiplied 
by  the  weight  of  the  body.  It  follows  that  a 
cannon  ball  weighing  only  a  pound  but  traveling 
at  very  high  speed  can  '  have  a  momentum  nu- 
merically as  great  as  a  locomotive  weighing 
thousands  of  pounds  more  than  the  cannon  ball 
but  traveling  at  a  greatly  reduced  pace. 

And  so  it  is  with  our  column  of  incoming  mix- 
ture; its  weight  is  only  a  little  bit,  but  its  speed 
is  very  high,  so  that  the  momentum  it  has  ac- 
quired during  the  intake  stroke1  is  appreciable. 
We  find  it  worth  while  to  take  advantage  of  this 
momentum  by  holding  the  inlet  valve  open  for  a 
brief  interval  after  the  piston  has  passed  bottom 
dead  center,  the  momentum  of  the  rapidly  mov- 
ing gas  column  carrying  more  fuel  into  the  cylin- 
der and  giving  us  a  fuller  charge. 

Just  how  much  "lag"  is  given  the  closing  of 
the  inlet  valve  with  relation  to  the 'bottom  dead 
center  depends  upon  the  size  and  the  speed  of  the 
engine,  the  size  of  the  valves  and  the  design  of 
the  inlet  port  and  gas  passages.  It  varies  con- 
siderably in  ^different  engines. 

In  a  comparatively  few  instances  this  same 
principle  is  applied  in  the  case  of  the  exhaust 
valve;  it  is  held  open  for  a  brief  interval  after 
top  dead  center  is  passed  so  that  the  momentum 


Valves  and  Valve  Mechanism.       91 

of  the  gases  passing  through  the  exhaust  piping 
will  aid  in  clearing  the  cylinder  and  will  tend 
to  create  a  partial  vacuum  behind  it  which  helps 
to  pull  in  the  fresh  gas  charge  when  the  inlet 
valve  is  opened.  Sometimes  the  inlet  valve  ac- 
tually begins  to  open  before  the  exhaust  valve 
is  fully  closed,  but  this  is  rarely  encountered  in 
anything  except  very  high  speed  racing  engines, 
since  it  tends  to  make  the  engine  hard  starting 
and  interferes  with  smooth  operation  when 
throttled  do\vn  for  low  speed  and  idling.  As  a 
rule,  as  was  said  before,  the  exhaust  valve  is  de- 
signed to  close  on  top  dead  center  and  the  inlet 
valve  to  open  just  at  that  point  or  a  shade 
afterward. 

But  it  is  of  very  great  value  to  thoroughly 
clear  the  cylinder  of  all  the  burned  gases  after 
the  power  stroke.  And  it  is  true  also  that  as  the 
piston  starts  down  on  the  power  stroke  the 
effective  pressure  of  the  gases  drops  off  very 
rapidly,  so  that  when  the  crank  is  nearing  the 
bottom  dead  center  the  pressure  is  not  really 
worth  while  taking  advantage  of.  It. is  found 
much  better,  in  the  way  of  smooth  operation  and 
economy,  to  open  the  exhaust  valve  while  the 
piston  has  considerable  distance  still  to  travel 
on  the  power  stroke  so  as  to  give  ample  time  for 
.the  spent  gases  to  escape;  this  also  tends  to 
make  for  cooler  running,  since  the  lower  sec- 
tion of  the  cylinder  is  not  exposed  to  such  in- 
tensely hot  gases.  The  "lead"  which  the  exhaust 
valve  opening  is  given  on  the  bottom  dead  center 
varies  greatly  in  engines  of  different  design  just 
as  the  "lag"  given  the  inlet  valve  opening  varies. 

The  timing  of  the  valves  is  a  matter  with 
which  the  tractor  owner  or  operator -has  prac- 
tically nothing  to  do.  The  timing  determined  on 
by  the  factory  engineer  is  brought  about  by  the 


92 


Tractor  Engines. 


design  of  the  cams  themselves,  the  mounting  of 
the  cams  "with  respect  to  each  other  on  the  cam- 
shaft and  the  mesh  of  the  timing  gear  wheels. 
This  latter  point  is  important  to  the  owner,  since 
if  the  engine  is  taken  apart  and  the  timing  gear 
mesh  disturbed,  it  is  important  that  in  putting 
the  engine  together  again  they  be  properly 
meshed  or  else  none  of  the  valves  on  the  engine 
will  be  timed  to  open  or  close  at  the  proper  time 
with  relation  to  the  piston  travel. 

The  exact  set- 
ting of  these  tim- 
ing gears  is  in- 
dicated both  in 
Figure  64  and  in 
Figure  66.  It 
will  be  found  that 
on  the  larger 
camshaft  wheel 


F1G.66 


Fig.    66.      Method   of   meshing   tim- 
ing gears  to  time  engine  correctly. 


there  is  a  punch 
mark  on  the  wheel 
rim  adjacent  one 
of  the  hollows  in- 
to which  the  teeth 
of  the  pinion  fit. 
On  the  crank- 
shaft pinion  one 
tooth  will  be  simi- 
larly marked  with 
a  punch  mark.  The  proper  mesh  of  the  gears 
is  accomplished  when  the  punch-marked  tooth  is 
caused  to  mesh  with  the  punch-marked  hollow 
on  the  camshaft  gear.  Once  this  relation  is 
established,  all  the  valves  on  all  the  cylinders  will 
be  perfectly  timed,  for  it  will  be  remembered 
that  all  the  cams  are  forged  integral  with  the 
camshaft. 

It  is  well,  in  taking  the  engine  apart,  to  make 


Valves  and  Valve  Mechanism.       93 

sure  that  the  timing  gears  are  punched.  If  not, 
punch-mark  them  as  outlined  above  before  un- 
meshing  them  so  that  they  can  be  put  back  in 
proper  mesh.  This  applies  to  other  gears  as  well. 

A  point  that  should  be  borne  in  mind  is  that 
there  is  always  a  clearance  left  between  the 
lower  end  of  the  valve  stem  and  the  upper  sur- 
face of  the  push  rod  or  tappet;  this  point  is 
made  clear  by  referring  to  Figure  65.  The  rea- 
son for  this  clearance  is  that  the  valve  stem  is 
going  to  expand  under  the  heat  and  if  it  we're  in 
actual  contact  with  the  tappet,  due  to  this  expan- 
sion, the  head  would  be  raised  slightly  from  the 
cylinder  seat  and  this  would  result  in  leakage. 
It  is  highly  important  that  there  be  a  clearance 
at  this  point  and  also  important  that  the  clearance 
be  maintained  within  certain  definite  limits.  If 
it  is  too  small,  the  expansion,  especially  in  the 
case  of  the  exhaust  valves,  which  get  tolerably 
hot,  will  be  sufficient  to  wipe  it  out. and  the  valves 
will  ride  on  the  tappets  and  leak.  If  it  is  too 
large,  the  tappet  will  not  come  in  contact  with 
the  valve  stem  as  quickly  as  it  should  and  the 
valve  will  open  late  as  a  consequence.  By  the 
same  token,  when  the  valve  is  being  closed,  the 
tappet  will  reseat  the  valve  too  quickly  so  that 
the  valve*will  not  stay  open  as  long  as  it  should 
and  a  loss  of  power  and  a  tendency  for  the  en- 
gine to  overheat  will  be  one  result;  noisy  oper- 
ation due  to  the  slap  of  the  tappets  against  the 
ends  of  the  valve  stems  will  be  another  annoying 
result. 

The  tappet  clearance,  as  it  is  -called,  should  be 
between  1/16  and  1/32  of  an  inch,  .preferably 
as  close  to  the  smaller  dimension  as  possible.  It 
will  vary  on  different  engines,  but  this  is  a  fair 
average.  It  is  measured  by  inserting  a  slip  of 
metal  of  the  proper  thickness  between  the  tappet 


94  Tractor  Engines. 


top  and  the  valve  stem  (Figure  67).  The  clear- 
ance is  properly  adjusted  when  the  engine  leaves 
the  factory,  but  it  will  be  affected  both  by  wear 
of  the  tappet,  cam  and  valve. stem,  causing  en- 
largement, naturally,  and  by  valve  grinding, 
which  lowers  the  valve  with  relation  to  the  cylin- 
der and  causes  a  diminishing  of  the  clearance. 

Attention  to  Valves — The  valves  require  more 
or  less  regular  attention.    It  is  essential  that  they 


n 
1 1  >P 

EiLL,         IB   ;" 


Fig.  67.     Adjusting  tappet  clearance  on  Waukesha  engine. 

seat  properly  in  the  cylinder  seats  in'  order  to 
prevent  leakage  of  the  compressed  gases  on  the 
compression  stroke  and  the  explosive  pressure  on 
the  power  stroke,  for  leakage  means  impaired 
power  and  loss  of  snap  and  "pep"  in  the  opera- 
tion of  the  engine. 

Valve  grinding  on  any  engine  is  not  a  diffi- 
cult matter.  To  accomplish  it,  first  drain  the 
engine,  then  remove  the  cylinder  head  in  the 
same  manner  as  indicated  for  carbon  removal 
under  cylinder  repairs,  exposing  the  top  or  heads 


Valves  and  Valve  Mechanism.       95 

of  the  valves  where  possible.  On  the  left  side 
of  the  engine  will  be  found  two  valve  covers; 
pressed  steel  plates  held  in  place  with  two  thumb 
screws.  They  should  be  removed,  exposing  the 
valve  springs  and  upper  ends  of  the  cam  fol- 
lowers. Now  with  a  valve  lifting  tool,  with 
fork  placed  under  the  valve  stem  and.  chain  or 
link  fulcrum  adjusted  so  that  you  get  a  good 
purchase  (Figure  68),  lift  the  valve  spring,  hold- 
ing down  the  valve  head.  Holding  the  spring 
in  the  raised  position,  pull  out  the  pin  passing 


Fig.  68.     Tools  for  removing  valve  cups  and  valves. 

through  the  lower  portion  of  the  valve  stem 
and  which  holds  the  valve  spring  washer  on  the 
stem.  Release  the  spring  and  lift  out  the  valve 
which  will  then  be  free.  » 

It  is  well  to  remove  all  the  valves  at  once; 
they  are  numbered,  and  the  cylinder  seats  are 
numbered  to  correspond,  so  that  no  difficulty  will 
be  experienced  in  getting  them  back  in  proper 
order.  Now  take  some  coarse  valve  grinding 
paste  and  apply  a  thin  coating  of  it  evenly  all 
around  the  bevel  surface  of  the  valve  and  re- 
place it  in  position.  Then  with  a  valve  grinding 
tool,  which  is  a  brace-like  tool  with  a  head  pro- 


96 


Tractor  Engines. 


vided  with  two  prongs  which  are  adapted  to  fit 
into  the  two  holes  formed  in  the  valve  head 
(sometimes  the  head  is  slotted  to  take  a  screw- 
driver bit)  rotate  the  valve  back  and  forth  from 
a  quarter  to  a  half  revolution,  Figure  69.  Do 
not  rotate  it  to  the  full  revolution,  as  it  is  apt 
to  cause  scratching  of  the  valve  and  its  seat. 
After  half  a  dozen  twists  of  this  nature,  lift  the 
valve  from  its  seat  and  put  it  in  another  position 
and  repeat  the  operation. 

Continue  this  process 
for  a  while,  then  wash  off 
the  valve,  wipe  off  the 
seat  and  note  the  condi- 
tion. When  the  valve  is 
right,  the  bevel  surface 
should  show  a  ring  of 
contact  with  the  seat  ex- 
tending entirely  around 
the  valve,  of  oxidized  sil- 
ver appearance,  free  from 
pit  marks  and  black  lines 
and  free  from  scratches 
and  ridges.  The  seat 
should  also  be  free  from 
pits  and  scratches.  When 
this  result  has  been 
achieved,  wash  off  the 
coarse  paste  and 


f^f/IVG   rc> 


Fig.      69.         Method 
grinding  valve  to  seat. 


of 


the  fine  or  finishing  paste  and  grind  for  a  while 
to  remove  any  slight  marks  resulting  from  the 
use  of  the  coarse  paste. 

When  all  the  valves  have  been  ground  in,  put 
them  back  in  the  cylinder  and  proceed  to  put  on 
the  valve  springs,  washers  and  pins  by  the  same 
method  as  they  were  r.emoved.  Then  replace  the 
cover  plates  and  the  cylinder  head,  water  pipe 
and  plug  cables. 


Valves  and  Valve  Mechanism.       97 


Fig.  70.    Valve  grinding  shown  in  picture.    1st.    Remove  valve 
plug,  by  using  a  short  flat  bar. 

Care  should  be  taken  in  grinding  in  the  valves 
to  see  to  it  that  none  of  the  grinding  paste  gets 
into  the  cylinders  or  the  valve  stem  guides.  If 
only  a  little  paste  is  used  at  a  time,  and  wash- 
ing off  the  valve  and  valve  seat  is  carefully 
done,  there  will  be  no  trouble  on  this  score.  An- 


Fig.  71.  2d.  Remove  valve  spring  by  turning  engine  over  until 
the  spring  is  compressed  to  its  utmost.  Place  a  short  piece  of 
gas  pipe  (sawed  as  per  illustration)  between  the  spring  and  crank 
case  to  hold  spring  in  a  compressed  condition,  then  turn  motor 
over  until  the  key  can  be  removed  from  the  valve  stem.  It  is 
not  necessary  to  remove  the  spring  when  grinding. . 


98 


Tractor  Engines. 


other  point  to  watch  is  to  make  sure  that  the 

™  "erindTJ   Vree  from  the  cam  when  £ 

are    grinding.      Sometimes    the    valve    will "  he 

shghtly  raised  by  the  cam,  when,  of  cour  e    aH 

he  grinding  in  the  world  will  noi  put  the  valve 

n  good  condition,  since  it  is  simply  rotating  on 

the  valve  stem  and  not  on  its  seat 


Valves  and  Valve  Mechanism.       99 

Figures  70  to  74  illustrate  the  method  to  fol- 
fow  in  an  engine  with  horizontal  cylinders  and 
heads  not  removable,  while  Figure  75  shows 
the  method  to  pursue  with  a  valve-in-head 
engine. 

If  the  valves  are  very  badly  ridged  and  the 
valve  seats  are  in  poor  condition,  reseating  must 


Fig.  74.  6th.  Use  a  wide-faced  screwdriver-shaped  iron,  in  a 
common  brace.  7th.  Press  valve  against  valve  sear  and  give 
a  turn  to  the  right,  release  pressure,  then  press  again  and  turn 
to  the  left.  Keep  this  up  until  a  good  seat  is  made.  8th.  When 
the  grinding  is  finished,  remove  the  valve  and  clean  away  all  the 
valve  grinding  compound  so  it  does  not  get  down  into  the 
combustion  chamber  and  get  to  cutting  the  cylinder  rings  or 
piston. 

be  resorted  to.  A  reseating  tool  can  be  obtained 
at  any  supply  store ;  it  is  simply  a  tapered 
reamer.  Care  should  be  exercised  in  using  it 
not  to  take  too  deep  a  cut,  which  may  affect  the 
clearance  between  the  valve  stem  and  the  tappet 
and  make'  shortening  the  valve  stem  necessary. 
A  valve  truing  tool  is  made  for  putting  the  valves 
into  good  condition ;  it  acts  in  a  manner  similar 


100 


Tractor  Engines. 


to  the  reseating  tool  except  that  instead  of  fitting 
into  the  seat  and  being  turned  around,  the  valve 
fits  into  the  tool  and  is  rotated  against  several 
cutting  edges  which  correctly  bevel  it.  After 
reseating  the  cylinder  seats  and  trimming  down 
the  valves  properly,  they  must  be  ground  in  to  a 
perfect  fit  as  indicated  above,  since  the  cutting 
tools  do  not  leave  them  in  condition  to  seat 
perfectly. 

If  a  good,  true  lathe  is  handy,  there  is  no  need 

.     for    using    a 

special  tool  to 
trim  down  the 
valves,  since 
they  can  be 
mounted  in 
the  chuck  of 
the  lathe  and 
rebeveled 
with  little  or 
no  trouble. 
Care  should 
be  exercised 
to  set  the 
slide  rest  on 
the  lathe  to  the  correct  angle  to  insure  a  perfect 
fit  of  the  bevel  surface  on  the  valve  with  the 
bevel  of  the  cylinder  seat ;  care  should  also  be 
used  not  to  mar  the  valve  stems  when  mounting 
them  in  the  lathe  chuck. 

If,  when  the  valves  have  been  removed,  it  is 
found  that  the  head  is  warped  so  badly  that  trim- 
ming down  the  valve  will  not  bring  it  into  proper- 
shape,  the  best  plan  is  to  discard  it  and  replace  it 
with  a  new  valve.  Sometimes  it  will  be  found 
that  the  head  is  not  perfectly  true  with  the  stem. 
This  can  generally  be  corrected  by  replacing  the 
valve  in  the  cylinder,  making  sure  that  it  is  off 


.     -  "iinnr 


COMPOUND 


Fig.    75.      Grinding    valves    on    "valve-in- 
head"  engine. 


Valves  and  Valve  Mechanism.     101 

the  cam,  and  giving  it  a  good  sharp  whack  in  the 
middle,  using  a  soft  drift  of  brass  or  mild  rolled 
steel  to  take  trie  actual  hammer  blow  and  protect 
the  cylinder  against  damage  should  the  hammer 
_  aim  be  poor.  Where  the  valve  stem  is  found  to 
be  badly  bent,  it  is  best  to  insert  a  new  valve  and 
not  to  bother  with  the  old  one,  as  it  is  very  likely 
to  stick  in  its  guide  and  render  the  cylinder  in- 
operative. When  grinding  the  valves  and  before 

replacing  them,  re- 
move all  the  car- 
bon deposit  from 
both  the  upper  and 
lower  sides  of  the 
valve  head  and 
clean  the  valve 
stem,  removing  any 
carbonized  oil  and 
roughness  with  a 
strip  of  emery  cloth 
used  as  shown  in 
Figure  76.  The 
emery  cloth  should 
be  carefully  used 
so  as  not  to  take 

too  much  off  the  valve  stems,  for  it  is  essential 
that  they  be  a  comparatively  tight  fit  in  the  valve 
stem  guides.  There  should  just  be  freedom 
enough  for  them  to  slide  up  and  down  easily 
without  any  tendency  to  stick;  the  looseness 
.  should  not  be  appreciable. 

If  any  of  the  valve  springs  are  found  to.  be 
weak  and  not  of  the  same  length  as  the  average 
spring,  it  is  well  to  replace  the  poor  ones  with 
new  springs.  A  weak  spring,  especially  on  an 
exhaust  valve,  will  have  a  tendency  to  cause  the 
engine  to  lag  and  run  unsteadily,  the  cause  of 
which  sluggish  action  is  difficult  to  locate. 


FIG. 


Fig.    76.     Method    of    polishing 
the  valve  stems. 


102 


Tractor  Engines. 


Generally,  valve  grinding  and  carbon  removal 
are  done  at  the  same  time,  since  both  will  be 
necessary  at  about  the  same  intervals  and  both 
require  disassembling  the  engine  to  about  the 
same  degree.  It  is  well,  therefore,  to  count  on 
grinding  in  the  valves  each  time  the  engine 
taken  down  for  carbon  removal. 

While  the  method  of  checking  up  on  the  tim- 
ing of  the  valves  will  differ  with  every  individual 
make  of  engine,  as  indeed  the'  timing  of  the 
valves  will  differ,  if  the  method  to  be  followed  in 
any  one  engine  is  applied  to  other  makes,  the 
tractor  operator  will  not  be  far  from  wrong.  It 
.is  a  fact  that  with  most  engines  the  timing  of 
the  valves  with  relation  to  the  crankshaft  is  in- 
dicated by  distinct  markings  on  the  flywheel 
which  show  exactly  when  a  valve  should  open 
and  close,  and  give  indication  of  wrong  timing 
in  case  loss  of  power  cannot  be  attributed  to  any 
other  cause.  The  following  method  applies  to 
the  Twin  City  tractor  engine  and  indicates  clearly 
the  procedure  on  similar  motors : 

Markings  on  the  Flywheel — The  diagram, 
Figure  77,  shows  the  points  at 
which  the  valves  in  one  cylin- 
der open  and  close.  It  must 
always  be  remembered  that  it 
takes  two  complete  revolutions 
to  complete  a  four-cycle  phase. 

Now  suppose  the  center 
mark  on  the  flywheel  is  in  line 
with  the  pointer  located  on  the 
center  line  of  the  motor.  By 
rotating  the  flywheel  to  the 
right,  the  first  mark  indicates 
the  point  at  which  the  exhaust 
valve  just  closes-. 

The  next  mark  is  the  point 


Valves  and  Valve  Mechanism.     103 


Fig.  78.     Timing  diagrams  for  Twin  City  engines. 

at  which  the  intake  valve  is  just  commencing  to 
open  and  remains  open  (which  is  the  suction 
stroke)  until  the  intake  closing  mark  is  reached, 
which  is  located  past  bottom  dead  center  or  op- 
posite the  intake  opening  mark.  Continuing  to 
rotate  compresses  the  charge  until  the  top  center 
mark  is  reached,  when  the  electric  spark  ignites 
the  charge. 

When  starting  a  motor  the  spark  is  retarded 
or  takes  place  after  piston  is  on  top  center,  but 
when  motor  is  up  to  speed  and  the  maximum 
power  is  required,  the  spark  takes  place  before 
top  center  is  reached,  which  is  the  advance  posi- 


Fig.  79.     Timing  diagrams  for  Twin  City  engines. 


104  Tractor  Engines. 

tion.  This  can  be  done  because  the  high  speed 
makes  it  possible  to  reach  top  center  and  past 
before  the  gas  is  really  ignited  and  expanded. 

Advancing  the  spark  too  far  will  make  the 
motor  pound,  which  is  caused  by  the  explosion 
taking  place  too  early  and  the  full  force  is  ap- 
plied when  the  piston  is  still  compressing  the 
charge. 

Continuing  to  rotate  until  the  next  point  is 
reached  is  the  exhaust  just  commencing  to  open. 
This  will  remain  open  until  the  exhaust  closing 
point  is  again  reached. 

To  place  any  one  piston  at  the  top  center,  ro- 
tate the  flywheel  until  the  intake  closes  and  the 
center  mark  on  the  flywheel  next  reached  will 
bring  that  piston  in  the  top  center  position. 

The  position  of  the  marks  on  the  flywheel, 
measuring  along  the  circumference,  is  as  follows : 

T.  C.40&60  T.  C.25  T.  C.  IS 

Intake  opens  past  top  center 3^  3>y2  1^4 

Intake  closes  past  lower  center. .    4%2  22%2 

Exhaust  opens  before  lower  center   9lVs2  T7A  6%6 

Exhaust  closes  after  top  center..    2%4  !31/&2  U/LQ 

These  are  illustrated  graphically  in  Figures 
78  and  79. 

EXACT  SETTING  OF  VALVE  FOR  PROPER  TIMING 
ON  MOTOR  OF  BULL  TRACTOR. 

Set  so  that  exhaust  valve  opens  36°  before 
center. 

Set  so  that  exhaust  valve  closes  8°  after  center. 
Set  so  that  intake  valve  opens  14°  after  center. 
Set  so  that  intake  valve  closes  20°  after  center. 

INCHES  ON  FLYWHEEL. 

36°— 85/32  inches.      .  8°r=l13/16  inches. 
14°=33/i6  inches.       20°=41V32  inches. 


Valves  and  Valve  Mechanism.     105 


Fig.   80.      Timing  of  Bull  tractor  engine. 


Time  of 
opening  or 
closing,  stated 
as  before  and 
after  center, 
refers  to  di- 
rection of 
motor  rota- 
tion. 

All  opening 
and  closing 
distances 
shown  should 
b  e  measured 
on  flywheel 

rim  only  and  from  center  arrow.  Never  remove 
flywheel  from  crankshaft  without  marking  posi- 
tion so  you  will  get  it  back  just  as  it  was  before 
rempved. 

Crankshaft   and   camshaft   gears   are   marked 
and  set  as  follows : 

Short  or  R.  H.  shaft  set  to  marks  Nos.  1. 
Long  or   L.   H.   shaft   set  to  marks    Nos.   2 
(Figure  80). 

After  the  valve  grinding  operation,  of  course, 
it  always  will  be  necessary  to  readjust  the  valve 

tappet  clear- 
ance  to  bring 
it  back  to  the 
manufacturer's 
specifications. 
Like  the  valve 
timing  check- 
ing, the  method 
to  be  followed 
in  effecting 
this  adjustment 
will  depend  to 


Fig.     81.     Adjusting 
overhead  valve  engine. 


push    rods    on 


106  Tractor  Engines. 

a  greater  or  less  extent  on  the  type  of  engine, 
and  especially  on  the  type  of  valve  arrangement 
employed. 

Figure  67  indipates  clearly  the  method  to  be 
followed  in  effecting  the  adjustment  on  an  L- 
head  engine,  a  rule  or  stick  being  employed  to 
determine  the  position  of  the  piston  with  rela- 
tion to  the  stroke  and  a  feeler  gauge  used  to  de- 
termine the  proper  clearance.  The  adjustment 
of  the  tappets  is  made  by  opening  the  locknut 
holding  the  tappet  adjusting  screw,  in  place  on 
top  of  the  tappet  and  unscrewing  the  screw 
slightly  to  take  up  some  of  the  clearance  in  case 
of  wear,  or  screwing  it  down  in  case  the  adjust- 
ment is  too  tight.  Figure  81  shows  how  the  ad- 
justment is  made  in  the  case  of  an  overhead 
valve  engine,  the  picture  illustrating  the  method 
of  adjustment  used  in  the  case  of  the  Case 
10-18  model. 


CHAPTER  V. 

About  the  Fuel  System. 

Some   Thoughts   on  the   Fuel  Burned   in  Tractor 
Engines  and  the  Means  for  Obtain- 
ing Best  Results. 

WHILE  in  the  automobile  field  we  find  that 
gasoline  is  the  universal  fuel,  and  that 
practically  every  make  of  car  and  truck  is 
adapted  to  burn  this  light  hydrocarbon  fuel  and 
none  other,  this  standardization  of  fuel  is  by  no 
means  apparent  in  the  tractor  industry. 

The  reason  is  not  hard  to  find.  The  tractor 
engine,  operating  as  it  does  on  almost  full  load 
throughout  the  en- 
tire day,  consumes 
considerable  fuel 
(Fig.  82)  ;  if,  then, 
we  employ  a  low- 
cost  fuel  as  against 

a    hicrh-rnct   nr»f»  FiS-    82-      The    gasoline    tank 

ne'  tells    the    story.      Exact    relative 

Other      thing's      being"  size  of  gasoline  and  oil  fuel  tanks 

i      rr6                    r  on  the   14-28   Oil   Pull  Tractor. 

equal,  the  cost  of 

operation  of  the  tractor  is  greatly  reduced. 

As  has  been  repeatedly  pointed  out  in  the  case 
of  the  tractor  engine,  flexibility  is  not  required 
to  anywhere  near  the  same  extent  as  with  the 
automobile  engine ;  the  use  of  kerosene,  therefore, 
is  not  at  all  objectionable,  always  provided  the 
means  for  handling  it  are  sufficiently  well  carried 
out  so  the  engine  will  idle  while  hitches  are  being 
made,  and  other  adjustment  effected  preparatory 

(107) 


108  Tractor  Engine's. 

to  starting  in  on  the  hard  work,  and  immediately 
pick  up  and  carry  the  full  load  without  faltering 
or  loading  up. 

Where  kerosene  has  failed  as  a  motor  fuel  for 
tractor  service,  the  fault  has  been  that  idling 
was  generally  followed  by  bad  operation,  due  to 
the  reduction  of  temperatures,  so  that  when  the 
throttle  was  opened  to  give  the  fuH  load,  the 
heavy  fuel  was  not  properly  handled. 

An  internal  combustion  tractor  motor  to  per- 
form the  function  of  burning  kerosene  in  the 
most  successful  and  advantageous  manner  must 
embody  in  its  design  and  construction  the  fol- 
lowing elements: 

1.*  A  double  carburetor  with  one  side  con- 
nected to  the  gasoline  supply  tank,  which  can 
be  properly  adjusted  and  used  for  starting  and 
heating  up  the  engine. 

2.  The    other    carburetor    connected    to    the 
kerosene  or  distillate  supply  tank  and  properly 
adjusted  so  that  the  intake  air  lines  to  the  motor 
may  be  instantaneously  switched  from  communi- 
cation with  one  carburetor  to  the  other,  as  the 
circumstances  may  require. 

3.  The  pipe  lines  from  the  kerosene  or  dis- 
tillate tank  must  be  through  some  portion  receiv- 
ing heat   from  the   exhaust  that   will   raise   the 
temperature   of   this   low-grade    fuel  to   a  point 
not  above  90  degrees  F.,  nor_below  75  degrees  F. 

4.  The    kerosene    carburetor    must    have    its 
inlet  connected  to  a  housing  around  the  exhaust 
pipe    so   that  .  when   the    exhaust   pipe   becomes 
heated 'the  air  passes  into  the  carburetor  at  a 
temperature  not  below  80  degrees. 

5.  With  the  air  and  the  fuel  at  the  respective 
temperatures  above  given,  meeting  in  the  carbu- 
retor, the  mixture  is  readily  formed. 


About  the  Fuel  System.          109 


6.  The  mixture  thus  formed  must  be  turned 
into  gas  (air-charged  kerosene  is  not  yet  a  gas). 
Therefore,  in  traveling  through  the  intake  pipe, 
it  must  be  brought  into  contact  with  the  surfaces 
of  the  intake  pipe,  made  hot  on  the  exhaust  pipe 
(called  a  gasifier — Figure  83).  Passing  over 
these  heated  corrugated  surfaces  in  a  circular 
path  and  finally  traveling  upwards  into  the  cylin- 
« der,  the  centrifugal  action  throws  the  heavier 
particles  of  kerosene  against  the  heated  wall,  and 

the  heat  transforms 
the  kerosene  -  charged 
air  into  a  dry  gas 
which  will  instantane- 
ously fire  and  burn 
quickly  and  completely. 

7.  In   the   passage- 
way between  the  gasi- 
fier and  the   intake 
valve,  a  valve  must  be 
provided    through 
which  outside  air   can 
be  taken  in,  which  will 
temper   this    gas   mix- 
Fig.  83.     Cross-section  of  the.    tUre     and     re<JUCG     th<T 

Avery  gasifier.  temperature  of  it,  and 

A-Fuei  mixture  coming  from   thereby    prevent    the 

carburetor  and  entering  gasifier.  1QSS  thrOUgh   expansion 

B — Fuel     mixture     thoroughly  & 

gasified  and  entering  cylinder.  due  tO  the  temperature 

.J-Exhaust  coming  from  cyl-  required    to    gasify    the 

grMitS?-  ™fure.  -m 

8.  Provision  for  in- 
jecting water   (Fig.  85)   with  the  kerosene  and 
low-grade  fuels  is  necessary  to  prevent  carbon 
deposits  and  knocking  due  to  preignition.     It  is 
not  necessary  to  start  the  water  for  a  few  min- 
utes, and  under  some  conditions  of  temperature 
very  little  water  is  required.     When  preignition 


110 


Tractor  Engines. 


takes  place,  water  is  required,  but  only  just  in 
sufficient  quantity  to  prevent  the  knock.  Too 
much  water  is  indicated  by  a  white  vapor  through 
the  exhaust  of  the  engine. 

9.     The  thermo-syphon  system   of  circulating 


INTAKE  ^—^M  OIF  OLD 


f/G.  84 


Fig.  84.  Section  through  Buckeye-Deppe  Integrator,  showing 
carburetor  arrangement  for  heating  the  fuel  and  air  and  the  me- 
chanical atomizer  in  the  form  of  a  whirling  fan  placed  above  the 
special  center-opening  throttle. 

the  cooling  water  is  beneficial  in  the  matter  of 
burning  kerosene,  because  it  automatically  starts 
the  water  circulating  as  soon  as  sufficient  heat 
has  been  generated  within  the  engine  for  burn- 
ing the  heavy  fuel.  A  circulating  pump  is  not 


About  the  Fuel  System.          Ill 


so  desirable,  because  at  certain  seasons  of  the 
year  the  cooling  water  is  circulated  too  fast  for 
the  temperature  prevailing  and  keeps  the  tem- 
perature of  the  water  top  low  for  good  operation, 
causing  condensation  in  the  cylinders;  and  when 
the  mixture  is  not  thoroughly  gasified,  or  be- 
comes condensed,  passage  of  the  fuel  by  the 
pistons  is  sure  to  be  the  result. 

While  kerosene  is  greatly  used  in  the  tractor 
field,   its   increasing   price,   bringing   it   well   up 

into  the  price  class 
with  the  lighter  gaso- 
line, coupled  with  the 
fact  that  certain  diffi- 
culties have  resulted 
in  a  good  many  in- 
stallations, because 
the  principles  on 
which  the  proper  op- 
eration of  a  kerosene 
engine  depended  have 
not  been  fully  under- 
stood, have'  resulted 
in  many  tractor  engi- 
neers retaining  the 
gasoline  fuel  in  pref- 
erence to  the  kerosene. 
Both  gasoline  and 
kerosene  are  more  or 
less  volatile  liquids  obtained'  from  the  distillation 
of  crude  petroleum.  This  heavy,  black,  smelly 
oil,  which  i$  drawn  from  wells  which  flourish  in 
several  parts  of  the  United  States  and  in  many 
foreign  countries,  is  put  into  a  still  and  the  tem- 
perature raised  until  certain  of  the  lighter  con- 
stituents contained  in  the  crude  oil  boil  off. 

The  first  vapors  to  pass  off  are  too  light  for 
use  as  motor  fuel,  and  the  general  process  is  to 


Fig.  85*.  Aultman-Taylor  heavy 
fuel  carburetor  showing  water 
injection  apparatus. 


112  Tractor  Engines. 

condense  them  and  pass  them  back  into  the  still, 
where  they  assist  in  breaking  up  the  heavier  con- 
stituents, producing  the  lighter  hydro-carbons 
which  are  adaptable  for  internal  combustion  en- 
gine use.  After  all  the  light  vapors  have  passed 
off,  the  temperature  is  elevated  slightly  and  boil- 
ing again  takes  place,  and  we  have  another  yield 
of  vapor  which,  when  condensed  in  a  cooling  coil 
outside%  the  still,  is  found  to  possess  a  boiling 
point  somewhat  higher  than  the  first  fraction  to 
come  over  on  the  starting  process. 

This  process  of  boiling  off  all  the  liquid  that 
will  distill  at  a  given  temperature  and  collecting 
the  condensed  liquid,  then  elevating  the  tempera- 
ture slightly,  causing  the  next  fraction  to  distill 
over  and  piping  the  distillate  into  another  tank, 
is  continued  until  nothing  is  left  in  the  still  ex- 
cept residue.  Roughly,  the  process  yields  gaso- 
line, naphtha,  benzine,  kerosene,  distillate,  heavy 
fuel  oil,  light  lubricating  oils,  medium  lubricating 
oils,  heavy  Jubricating  oils,  petroleum  jelly,  paraf- 
fin wax  or  asphaltum,  when  the  crude  oil  is  of 
asphalt  instead  of  paraffin  base. 

This  classification  is  very  rough.  As  a  matter 
of  actual  fact,  the  number  of  liquids  with  dif- 
ferent boiling  points  that  can  be  separated  from 
the  crude  oil  is  almost  indefinite,  so  that  any  one 
of  the  above-mentioned  oils  really  consists  of  a 
large  number  of  oils  of  different  boiling  points, 
with  these  boiling  points  falling  within  a  given 
range. 

Good  gasoline  will  consist  of  liquid^  with  boil- 
ing points  between  100  degrees  F.  and  350  de- 
grees F. ;  its  specific  gravity — weight  of  a  cubic 
inch  of  gasoline  at  a  given  temperature  compared 
with  an  equal  volume  of  water  at  the  same  tem- 
perature— or  its  Baume  reading,  which  gives  a 
similar  comparison  by  another  standard  or  scale, 


About  the  Fuel  System.          113 

has  no  bearing  on  its  value  as  a  fuel,  a  point 
which  the  average  operator  finds  it  hard  to  be- 
lieve. 

What  we  really  want  in  a  gasoline  motor  fuel 
is  one  which  will  vaporize  readily;  that  is,  one 
in  which  the  whole  body  of  the  fuel  will  vaporize 
within  a  comparatively  short  temperature  range. 
We  can  have  such  a  fuel,  and  its  gravity  as  given 
by  Baume  reading  may  be  56  degrees;  but  pro- 
vided the  boiling  points  of  its  various  constituents 
are  within  a  comparatively  short  temperature 
range,  and  the  maximum  temperature  is  not  so 
high  as  to  preclude  ready  vaporization  of  the 
fuel  at  ordinary  temperatures,  it  will  be  a  good 
fuel. 

If,  on  the  other  hand,  we  have  a  fuel  made 
up  of  one  distillate — say,  for  instance,  kerosene 
with  high  boiling  point  and  low  gravity — and 
some  other  hydro-carbon  such  as  first  comes  over 
from  the  still  with  very  low  boiling  point  and 
high  "Baume  test,  the  average  or  mean  Baume 
test  of  the  two  mixed  together  may  stand  as 
high  as  70  or  75  degrees  Baume  and  the  fuel 
will  not  be  as  good  for  motor  use  as  the  first 
with  lower  Baume  test.  The  reason  is  easily 
found;  the  lighter  portion  of  the  fuel  will  va- 
porize readily,  making  the  engine  easy  to  start, 
but  will  1'eave  behind  the  heavier  portion  of  the 
fuel,  not  so  readily  vaporized,  which  will  be 
troublesome. 

It  is  readily  seen,  therefore,  that  it  is  fallacious 
to  attempt  to  judge  the  quality  of  gasoline  by 
the  specific  gravity  or  Baume  tests,  either  of  which 
tests  are  carried  out  with  an  instrument  called 
a  hydrometer,  differently  graduated  in  accord- 
ance with  which  standard  is  adopted.  The  only 
reliable  test  to  determine  the  value  of  a  fuel  is 
the  distillation  test,  which  gives  the  range  of  the 


114 


Tractor  Engines. 


boiling  points  of  the  constituents  of  which  the 
fuel  is  composed. 

In  the  case  of  kerosene  fuel,  we  have  not  the 
real  need  to  worry  over  the  distillation  curve  or 
any  other  form  of  test,  for  it  is  a  fact  that  any 
engine  adapted  to  handle  kerosene  properly  will 
work  well  with  any  kerosene  which  the  present 
market  affords. 


.  '„  THROTTLE  STOP*'. 
THROTTLE  LEVEft  "---s 

NEEDLE  VALVE 

BiNOiN'G  NUT 
CHOKE  VALVE -LEVER 


TTLE  STOP  SCREW 


AIR  VENT 

FLOAT  VALVE  PLUG 


TAKE  OUT  SCREW 
fO  REMOVE. FLOAT 


CONNECTION 
TO  TANK 


.  86 


Fig.  86.     Carburetor  from  Case  10-18  tractor. 

% 

While,  as  indicated  above,  there  are  some 
special  conditions  to  be  taken  into  consideration 
when  kerosene  is  the  fuel  used,  in  the  broadest 
sense  the  principles  upon  which  the  vaporization 
of  the  fuel  depends  does  not  vary.  With  either 
fuel  in  tractor  application,  we  employ  a  carbu- 
retor (Figure  86)  to  assist  in  the  operation. 

The  purpose  of  the  carburetor  is  three-fold. 
It  is  a  fact  that  no  substance,  be  it  air  or  solid, 
will  take  fire  and  burn  until  converted  into  the 


About  the  Fuel  System.          115 

gaseous  state.  The  quicker  the  substance  is  con- 
verted into  the  form  of  a  gas,  the  more  rapid 
will  the  combustion  be.  It  stands  to  reason, 
therefore,  that  in  order  to  obtain  very  rapid  com- 
bustion of  our  fuel  we  must  convert  it  to  a  state 
where  it  will  be  very  rapidly  transformed  into  a 
true  gas  which  will  readily  take  fire  and  in  burn- 
ing liberate'  the  desired  quantity  of  heat  to  ac- 
complish the  work  on  the  top  of  the  piston. 

That  is  the  primary  function  of  the  carburetor. 
It  is  so  arranged  that  it  divides  the  liquid  into 
an  infinite  number  of  very  fine  particles ;  breaks 
it  up,  pulverizes  or  atomizes  it  so  that  the  fuel, 
being  held  in  suspension  in  the  air  after  emerg- 
ing from  the  carburetor  where  it  has  undergone 
this  treatment,  is  in  fine  condition  to  be  readily 
converted  into  a  true  gas.  This  result  is  brought 
about  in  very  much  the  same  manner  as  perfume 
is  sprayed  from  an  atomizer.  In  the  carburetor 
there  is  a  nozzle  which  corresponds  to  the  spray 
nozzle  of  the  atomizer,  and  the  rush  of  air  across 
the  orifice  of  this  nozzle  occasioned  by  the  suc- 
tion of  the  cylinders  when  the  pistons  are  going 
down  on  their  intake  strokes,  causes  the  fuel  to 
flow  from  this  nozzle  in  the  form  of  a  fine  spray, 
whic^h  is  taken  up  by  the  passing  air  column  and 
carried  into  the  cylinders. 

It  is  also  a  fact,  that  any  substance  which  is 
burning  combines  in  definite  proportions  with 
oxygen  gas  which  is  present  in  the  air.  For 
complete  combustion  of  any  fuel  a  given  amount 
of  this  gas  must  be  supplied  for  a  given  amount 
of  the  fuel ;  if  the  oxygen  is  drawn  from  the  air 
a  fixed  amount  of  the  air  sufficient  to  supply  the 
required  amount  of  oxygen  must  be  supplied  or 
else  the  combustion  will  not  be  complete. 

It  so  happens  that  with  gasoline,  in  order  to 
supply  sufficient  oxygen,  16  times  as  much  air 


116  Tractor  Engines. 

by  weight  is  required  as  of  gasoline.  Such  a 
mixture  of  gasoline  and  air,  with  the  fuel 
thoroughly  vaporized,  would  be  the  theoretically 
perfect  mixture.  There  is  present  in  the  air, 
however,  an  inert  or  inactive  gas  called  nitrogen, 
which  retards  the  speed  with  which  the  mixture 
will  burn,  and  in  order  to  counteract  the  slowing 
up  effect  of  this  inert  gas  it  is  necessary  to 
supply  a  greater  amount  of  fuel  than  one  part 
to  sixteen,  and  so  the  usual  carburetor,  when  in 
good  adjustment,  is  set  to  supply  approximately 
ten  times  as  much  air  by  weight  as  of  fuel ;  this 
is  the  practical  ideal  mixture,  while  the  16  to  1 
mixture  is  the  theoretical  ideal  one. 

The  second  function  of  the  carburetor  is  to 
proportion  the  amount  of  fuel  to  air  to  maintain 
this  correct  mixture  throughout  every  condition 
of  speed  and  power.  If  the  carburetor  does  not 
maintain  this  mixture  correct,  it  is  evident  that 
at  some  speeds  we  will  have  a  mixture  with  an 
excess  of  fuel  present  which  will  be  slow- 
burning,  sluggish  and  wasteful  of  fuel  and  we 
will  not  get  full  power  from  the  engine.  At 
other  speeds  we  will  get  a  mixture  with  an  ex- 
cess of  air,  whicrj  also  will  be  slow-burning  and 
from  which  we  will  not  get  sufficient  heat  and 
pressure  to  cause  the  engine  to  develop  *full 
power,  while  at  other  speeds  we  will  get  a  per- 
fect mixture  and  the  engine  will  perform  well. 

The  modern  carburetor  has  been  developed  to 
a  point  where  it  will  maintain  this  most  necessary 
constancy  of  mixture  proportions  throughout  the 
entire  speed  range  of  the  engine,  giving  us  flex- 
ible operation,  economy  from  the  fuel  standpoint 
and  maximum  power — but  above  all,  perfectly 
steady  and  reliable  operation,  with  no  tendency 
for  the  engine  to  falter,  stop  or  stall. 

The  carburetor  is  one  other  important   func- 


About  the  Fuel  System.          117 

tion  to  perform  which  is  sometirries  overlooked. 
It  incorporates  in  its  makeup  a  shutoff  valve 
applied  to  the  passage,  by  which  the  mixture 
leaves  the  carburetor  and  finds  its  way  to  the 
intake  manifold,  through  which  it  is  conducted 
to  the  cylinder.  This  is  the  throttle  valve,  and 
its  purpose  is  to  control  the  amount  of  mixture 
delivered  to  the  cylinders  and  consequently  the 
power  developed  by  the  engine  and  the  speed  or 
pulling  ability  of  the  engine. 

It  will  be  well,  perhaps,  to  give  some  thought 
to  basic  principles  on  which  carburetors  as  a 
whole  depend.  In  order  to  eliminate  complica- 
tions, for  the  present,  let  us  consider  that  the 
throttle  valve  is  missing  and  that  the  carburetor 
consists  of  a  simple  nozzle  or  jet  protruding  into 
an  air  passage  connected  with  the  cylinders.  If 
we  neglect  the  friction  of  the  air  piping,  it  is 
evident  that  the  amount  of  air  which  will  pass 
through  the  pipe  will  be  proportional  to  the  speed 
of  the  engine.  In  other  words,  the  engine  acts 
as  a  pump ;  at  a  given  number  of  revolutions  per 
minute  it  will  pump  a  certain  amount  of  air,  de- 
pending on  the  piston  displacement ;  at  double  that 
speed  it  will  pump  very  nearly  twice  as  much  air. 

The  force  which  is  actually  causing  the  air 
to  flow  into  the  cylinders  is  the  pressure  of  the 
atmosphere.  The  pistons  are  drawing  the  air 
out  of  the  manifold,  reducing  the  pressure  in 
the  manifold  from  about  15  pounds  per  square 
inch,  or  atmospheric  pressure,  to  something  less 
than  that  amount,  depending  on  the  speed  of  the 
engine.  Let  us  suppose  that  at  the  lower  speed 
cited  in  the  case  above,  the  pressure  in  the  mani- 
fold was  reduced  to  10  pounds  per  square  inch ; 
then  at  the  air  opening  on  the  carburetor  we 
have  an  effective  pressure  of  five  pounds  per 
square  inch,  causing  the  air  to  enter  and  'flow 


118  Tractor  Engines. 

through  the  tubing  or  piping  to  the  cylinders. 
If  now  we  double  the  speed  of  the  engine  we 
still  further  decrease  the  pressure  in  the  mani- 
fold, let  us  say,  to  five  pounds  per  square  inch, 
so  that  we  have  a  pressure  of  ten  pounds  per 
square  inch  forcing  the  air  through  the  piping; 
and  naturally  its  flow  will  be  somewhere  near 
double  the  rate  at  lower  speed  and  approximately 
twice  as  much  will  pass  through  in  a  given  time. 

This  reduced  air  pressure  in  the  manifold  is 
important,  as  is  also  its  variation  with  the  speed 
of  the  engine.  In  the  nozzle  which  projects  into 
the  air  pipe  we  have  the  fuel,  the  level  controlled 
so  that  it  stands  just  at  the  top  of  the  jet.  When 
the  air  pressure  is  reduced  in  the  manifold,  since 
"we  have  the  pressure  of  the  atmosphere  acting 
on  the  other  end  of  the  fuel  line  leading  to  the 
noaele,  w%e  naturally  have  a  pressure  exerted  to 
, force  the  fuel  out  of  the  nozzle  into  the  mani- 
fold where  it  mixes  with  the  rapidly  moving  air 
column.  The  fuel  is  atomized  by  passing  through 
a  comparatively  fine  nozzle,  sometimes  of  special 
shape.  This  atomization  is  furthered  by  the 
rapid  movement  of  the  air  column. 

Naturally,  at  higher  speeds,  with  the  manifold 
pressure  reduced,  we  are  going  to  have  more 
pressure  action  on  the  liquid  column,  tending  to 
cause  it  to  flow  at  faster  pace  and  in  greater 
quantity  into  the  manifold.  If  the  laws  govern- 
ing the  flow  of  air  through  tubing  under  reduced 
pressure  and  those  governing  the  flow  of  liquids 
through  nozzles  under  reduced  pressure  were  the 
'same,  it  is  evident  that  from  this  simple  arrange- 
ment we  would  get  a  constant  mixture  of  gasoline 
and  air  at  all  speeds.  k 

Such,  however,  is  not  the  case.  The  flow  of 
liquid  through  the  nozzle  increases  more  rapidly 
with  the  falling  off  in  manifold  pressure  than  the 


About  the  Fuel  System.          119 

flow  of  the  air  through  the  pipe  so  that  at  high 
speeds  we  get  a  mixture  with  an  excess  of  fuel, 
or,  as  we  say,  an  over-rich  mixture. 

If,  therefore,  we  adjust  the  fuel  nozzle  so  as 
to  give  us  the  correct  mixture  at  low  speeds,  it 
is  evident  that  at  high  speeds  we  are  going  to 
get  a  rich  mixture.  If,  on  the  other  hand,  we 
adjust  it  to  give  us  the  correct  mixture  at  high 
speeds,  at  low  speeds  the  mixture  is  going  to  be 


<BE:.  _.,  _  BINDING  NUT 

SECONDARY  '  ^•mEPPS  '•-    J^£  CHOKE  VALVE 

AIR  VALVE 


REMOVABLE  FLOAT 
VALVE  SEAT 


.Fig.  87.     Sectional  view  of  carburetor. 

lean — there  will  not  be  enough  fuel  for  the 
amount  of  air  supplied.  This  result  is  due  to  the 
difference  in  flow  between  the  air  and  the  liquid 
columns  under  the  differing  manifold  pressures. 
If  we  bear  this  relation  distinctly  in  mind,  we 
will  not  have  the  slightest  difficulty  in  thoroughly 
grasping  the  construction  and  the  principles 
of  operation  of  the  carburetor  applied  to  almost 
any  tractor  engine.  One  from  a  Case  10-18 


120  Tractor  Engines. 

tractor  is  shown  in  cross-sectional  form  to  make 
its  construction  plain,  in  Figure  87.  The  fuel 
enters  from  the  tube  leading  from  the  tank  at 
the  point  marked  "Float  valve"  and  flows  down 
into  the  bowl  of  the  carburetor.  In  this  bowl 
there  is  a  cork  float  in  the  shape  of  a  ring  to 
which  is  attached  a  small  lever  hinged  or  ful- 
crumed  to  the  top  of  the  float  chamber.  The  other 
arm  of  this  lever  is  arranged  to  press  against  the 
gasoline  intake  needle.  As  the  float  rises  with 
the  level  of  the  incoming  gasoline,  it  gradually 
brings  the  lower  or  pointed  end  of  this  needle 
into  contact  with  a  valve  seat,  clearly  indicated 
in  the  figure,  and  closes  off  the  gasoline  so  that 
no  more  can  enter  the  bowl.  This  float  mechan- 
ism is  so  arranged  as  to  maintain  a  constant  level 
of  the  fuel  in  the  float  chamber  at  all  times. 

The  air.  enters  the  carburetor  through  a  hori- 
zontal passage  on  the  side  marked  "Air  intake," 
and  this  passage  is  bent  downward  to  form  a 
well,  an4  at  the  same  time  its  diameter  is  de- 
creased so  that  at  the  deepest  section  of  the  well 
the  area  of  the  passage  is  at  a  minimum.  Just 
at  this  point  is  located  a  needle  valve  passing 
through  the  well  and  closing  the  gasoline  passage 
between  the  well  and  the  float  chamber.  Nor- 
mally, this  valve  is  opened  just  enough  to  provide 
sufficient  gasoline  for  full  power  operation  of 
the  engine.  The  needle  valve,  however,  permits 
of  very  accurate  regulation  of  the  amount  of  fuel 
which  can  enter  the  air  passage  from  the  float 
chamber. 

Coming  up  from  the  well,  the  air  passage 
broadens  out  again  and  takes  a  vertical  path,  and 
just  where  it  enters  into  the  comparatively  broad 
mixing  chamber  is  placed  a  hinged  valve,  called 
the  secondary  air  valve.  It  will  be  appreciated 
that  this  valve  will  be  fully  closed,  due  to  its 


About  the  Fuel  System.          121 

own  weight,  which  is  carefully  proportioned  to 
the  conditions  obtaining  on  the  Case  engine,  so 
that  the  passage  of  the  air  is  stopped  or  nearly 
stopped. 

Reference  to  the  diagram  will  show  that  the 
needle  valve  proper  is  surrounded  with  a  cylin- 
drical passage  or  air  bypass,  by  means  of  which 
a  certain  limited  quantity  of  air  can  pass  into  the 
mixing  chamber  from  the  well  even  with  the 
secondary  air  valve,  closed.  When  the  suction 
on  the  manifold  increases,  due  to  increased  work 
being  done  by  the  engine,  as  when  the  throttle 
is  opened,  the  air  valve  opens  automatically,  per- 
mitting an  increased  amount  of  air  to  enter  the 
mixing  chamber. 

The  "float  valve  is  so  arranged  that  it  main- 
tains the  mixture  exactly  at  the  proper  level  to 
permit  a  slight  overflow  into  the  well,  maintain- 
ing a  puddle  when  the  engine  is  not  in  operation. 
Considering  now  that  the  engine  is  cold,  the 
operator  will  turn  the  engine  over  and  the  enter- 
ing air  will  rush  through  the  well  at  very  high 
velocity,  due  to  the  constricted  passage.  The 
high  velocity,  however,  entails  a  drop  in  pressure, 
so  that  at  the  spray  nozzle  controlling  the  en- 
trance of  the  fuel  into  the  well  we  will  have  a 
partial  vacuum  formed.  The  flow  of  gasoline 
into  the  well  will,  therefore,  be  started  auto- 
matically the  instant  the  engine  is  turned  over, 
and  the  amount  flowing  will  depend  on  the  veloc- 
ity of  the  air  and  the  suction  which  it  creates  in 
the  constricted  passage. 

The  entering  air  will  impinge  on  top  of  the 
puddle  and  supply  the  excess  amount  of  gasoline 
to  air  mixture  in  order  to  provide  a  rich  mixture 
for  starting  while  the  engine  is  cold;  after  the 
first  few  revolutions,  however,  the  well  will  be 
sucked  dry  and  all  the  gasoline  supplied  will 


122  Tractor  Engines. 

come  through  the  needle  valve  and  the  spray 
nozzle.  But  at  the  spray  nozzle  the  air  passage, 
considering  low  speeds,  is  greatly  narrowed,  forc- 
ing the  air  to*  assume  very  high  speeds  through 
the  cylindrical  bypass  around  the  needle  valve. 
The  high  velocity  entails  great  suction  so  that 
sufficient  gasoline  is  drawn  through  the  needle 
valve  in-  order  to  provide  the  constant  mixture 
for  low  throttle  operation. 

The  opening  of  the  secondary  air  valve  pro- 
portions the  amount  of  air  flowing  directly  into 
the  mixing  chamber  to  the  amount  flowing 
through  the  bypass,  and  consequently  regulates 
the  suction  on  the  needle  valve  in  exact  accord- 
ance with  the  amount  of  air  flowing  to  provide 
just  the  correct  gasoline  flow  to  determine  a 
constant  mixture. 

From  the  carburetor  the  mixture  passes  into 
the  inlet  manifold,  which  is  a  branched  pipe 
leading  the  mixture  to  the  intake  port  on  each 
cylinder;  the  amount  of  mixture  entering  the 
manifold  is  controlled  by  the  throttle  valve,  which 
is  simply  a  disc  of  brass  of  a  diameter  substan- 
tially equal  to  the  internal  diameter  of  the  mix- 
ture passage  in  the  carburetor  and  mounted  on 
a  horizontal  spindle  which  when  turned  by  the 
lever  sets  the  disc  either  to  close  the  passage  or 
open  it,  or  to  give  any  desired  intermediate  open- 
ing as  required  by  the  operating  conditions  and 
the  amount  of  power  it  is  desired  to  take  from 
-the  engine.  As  a  matter  of  fact,  the  throttle 
valve  never  comes  to  a  fully  closed  position  when 
the  carburetor  is  in  correct  adjustment;  there  is 
always  a  slight  opening  maintained  by  a  screw 
adjusted  stop  on  the  throttle  lever  so  that  even 
when  the  throttle  control  lever  is  fully  closed, 
sufficient  fuel  will  pass  the  valve  to  keep  the  en- 
gine running  at  low  speed — idling,  as  it  is  termed. 


About  the  Fuel  System.          123 


A  second  butterfly  valve  is  placed  in  the  air 
intake  pipe  on  the  carburetor ;  it  is  called  a  choke 
valve  and  is  operated  by  a  lever.  Normally,  with 
the  engine  running,  regardless  of  speed,  this 
valve  stands  fully  open  and  is  held  so  by  a  spring. 
In  starting,  however,  especially  in  chilly  weather, 
it  is  desirable  to  provide  a  rich  mixture ;  consid- 
erably richer  than  the  running  mixture,  because 
with  cold  air  the  gasoline  is  harder  to  convert 
into  a  true  gas;  less  of  it  is  so  converted  and 
more  must  be  supplied  to  make  up  for  the 

deficiency.  Instead  of 
supplying  more  gaso- 
line by  opening  the 
needle  valve  further, 
the  choke  valve  is 
partially  closed  so 
that  less  air  is  sup- 
plied, which  also  has 
the  effect  of  reducing 
the  atmospheric  pres- 
sure in  the  mixing 
chamber  of  the  carbu- 
retor so  that  there  is 
a  large  flow  of  fuel 
into  the  well,  the  com- 
bined strangulation  of 
the  air  and  increased  flow  of  gasoline  giving 
the  necessary  rich  mixture  for  starting. 

The  cup  or  bowl  of  the  Linga  carburetor 
(shown  in  Figures  88  and  89)  has  three  com- 
partments— for  gasoline,  kerosene  and  water. 
Each  compartment  has  a  float. 

The  'gasoline,  which  is  used  for  starting,  and 
the  kerosene  are  both  supplied  to  the  engine 
through  a  common  opening  controlled  by  the  fuel 
needle  valve  (8).  The  water  is  fed  through  the 
water  needle  valve  (11). 


Fig.    88.     The    Linga   Vaporizer. 


124 


Tractor  Engines. 


To  change  from  gas- 
oline to  kerosene,  or 
the  reverse,  it  is  only 
necessary  to  tilt  the 
fuel  switch  (12)  from 
one  side  to  the  other. 
When  tilted  to  the 
right  it  holds  the  kero- 
sene needle  (10)  down 
on  its  seat,  which 
closes  the  opening  be- 
t  w  e  e  n  the  kerosene 
compartment  and  the 
fuel  needle  valve.  In 
this  position  the  gaso- 
line needle  (9)  is  lifted 
and  gasoline  is  admit- 
ted to  the  fuel  needle 
valve. 

If  the  fuel  switch  (13) 
is  tilted  to  the  left  the 
gasoline  passage  closes 
and  that  of  kerosene 
opens.  If  the  switch 
(13)  is  placed  in  a 
vertical  or  middle  po- 
sition the  vaporizer 
will  feed  a  mixture  of 
half  gasoline  and  half, 
kerosene. 

The  kerosene  needle 
valve  has  a  stronger 
spring  than  the  gaso- 
line needle,  so  ordinar- 
ily the  kerosene  pas- 
sage will  remain  open 
and  close  the  gasoline 
passage.  For  starting 


n<3. 39 


Fig.     89.      Sectional     view    of 
Linga  Vaporizer. 

Linga.  Vaporizer  Parts. 

1.  Bowl     with    three     compart- 
ments. % 

2.  Vaporizer  Body. 

3.  Auxiliary  Air  Valve. 
.    4.  Auxiliary  Air  Valve. 

5.  Valve  Cage* 

6.  Drip   Bell. 

7.  Nut. 

8.  Fuel  Needle  Valve. 

9.  Switch  Needle. 

10.  Switch   Needle. 

11.  Water  Needle  Valve. 

12.  Packing  Nut. 

13.  Fuel  Switch. 

14.  Fuel  Switch  Nut. 

15.  Throttle  Valve. 

16.  Throttle  Lever. 

17.  Throttle  Stud. 

18.  Throttle  Nut. 

19.  Connecting    link    or    throttle 
lever  shoulder. 

20.  Spring. 

21.  Spring. 

22.  Float  Valve  Screw. 

23.  Float  Needle. 

(•Bronze  Balls  are  used  on 
some  sizes). 

24.  Float  Arm. 

25.  Float. 

26.  Stud. 

27.  Compression  Coupling. 

28.  Throttle  Screw. 

29.  Drain  Cock. 


About  the  Fuel  System.          125 

on  gasoline  the  fuel  switch  must  be  tilted  to  the 
right  and  held  there  by  fastening  the  thumb  nnt. 

The  air  intakes  are  at  the  bottom.  The  ini- 
tial air  (about  one-fifth  of  the  total)  is  drawn 
through  the  nozzle  tube  in  the  center.  This  is 
the  hot  air  taken  from  a  jacket  around  the  ex- 
haust pipe.  The  fuel  is  drawn  into  this  hot  air 
jet  and  evaporated. 

The  auxiliary  air  is  admitted  through  the  two 
annular  slots  around  the  center  tube.  The  valves 
are  two  annular  rings  of  such  weights  as  will 
insure  the  best  running  of  the  engine  at  high 
and  low  speed. 

The  governor  on  the  engine  acts  directly  on 
the  butterfly  valve  of  the  carburetor.  You  will 
notice  a  little  projection  or  shoulder  fastened  to 
the  butterfly  valve  lever  by  means  of  a  nut. 
When  the  engine  is  running  idle  or  empty  the  but- 
terfly valve  or  throttle  closes  and  this  little  shoul- 
der strikes  the  fuel  switch,  tilting  it  just  a  trifle 
and  thus  admitting  a  small  amount  of  gasoline 
with  the  kerosene.  Thus  the  full  flexibility  of 
the  engine  is  preserved. 

The  carburetor  is  very  simple.  After  remov- 
ing the  hot  air  intake,  the  bowl  of  the  carburetor 
can  be  removed  by  turning  off  the  large  thumb 
screw  at  the  bottom.  A  screwdriver  is  the  only 
tool  required  to  remove  the  floats  and  valves  tp 
allow  cleaning  the  fuel  passages. 

The  Rumely  carburetor  used  on  the  Model 
14-28  tractor  is  very  simple,  and  is  free  from 
floats,  springs  and  internal  automatic  mechanism 
or  complicated  parts,  requiring  frequent  adjust- 
ment, or  changing  to  suit  damp  or  dry  weather. 
It  consists  simply  of  a  vertical  tube  of  peculiar 
internal  shape,  surrounded  by  three  divided 
chambers  for  kerosene,  water  and  gasoline,  each 
having  a  needle  valve.  Below  the  fuel  cham- 


126 


Tractor  Engines. 


bers  the  throttle  valve  is  placed,  which  is  coupled 
direct  to  the  governor  and  accurately  measures 
and  proportions  each  charge  of  mixed  fuel,  air 
and  water  that  goes  into  the  cylinders. 

The  gasojine  chamber  is  used  only  in  starting, 
and  as  it  has  no  other  use,  there  are  no  auto- 
matic means  for  getting  gasoline  into  it.  A 
bronze  plunger  pump  working  off  the  camshaft 
lifts  kerosene  and  water  to  the  carburetor,  the 
surplus  draining  back  through  overflow  pipes. 

A  jacket  on  the' exhaust  pipe  heats  the  intake 
air   with   means    for   regulating   the   amount   of 
heat.      This    is    necessary    in 
cold  weather  only. 

The  air  first  goes  through 
a  cleaner  where  the  dust  and 
grit  are  removed,  and  then 
enters  the  top  of  the  carbu- 
retor, passes  through  the  ven- 
turi  and  mixes  with  the  kero- 
sene and  water,  the  relative 
quantity  of  each  being  regu- 
lated by  the  governor  con- 
trolled throttle  valve  located 
in  the  lower  part  of  the  car- 
buretor. From  here  the  mix- 
ture goes  direct  to  the  com- 
bustion •  chamber  of  the  motor  to  be  consumed. 
In  appearance  it  is  merely  a  cylindrical  tube 
surrounded  by  the  fuel  chambers.  In  outward 
appearance  it  follows  general  lines  of  carburetor 
construction,  as  practiced  by  builders  of  internal 
combustion  engines.  The  internal  construction, 
however,  of  the  14-28  carburetor,  is  radically  dif- 
ferent from  that  of  carburetors  of  other  builders, 
as  Figure  90  fully  explains. 

Figure  90  shows  a  cross-section  of  the  14-28 
carburetor.  It  will  be  noted  that  the  central 


Fig.  90.  Sectional 
view  of  14-28  car- 
buretor. 


About  the  Fuel  System.          127 

cylindrical  passage  has  a  restricted  portion  form- 
ing a  venturi  tube.  The  oil  fuel  nozzle  is  located 
in  the  under  portion  of  the  venturi,  while  the 
water  nozzle  is  located  above. 

Due  to  the  peculiar  shape  of  this  passage  and 
the  relation  of  the  nozzles  to  it,  the  proper  quan- 
tity and  proportions  of  fuel  and  water  are 
automatically  fed  to  the  engine  at  all  times, 
regardless  of  load. 

The  action  of  the  engine  piston  produces  a 
partial  vacuum  in  the  carburetor  passage,  and 
this  relative  vacuum  in  the  zone  marked  A  varies 
with  the  load,  so  that  the  correct  proportion  of 
fuel  is  always  exactly  suited  to  the  existing  load. 

In  the  zone  above  the  venturi  marked  B,  a  rela- 
tively strong  vacuum  prevails  during  the  heavy 
loads,  but  decreases  very  rapidly  as  the  load  is  re- 
duced. At  the  low  loads  the  vacuum  is  reduced  to 
such  an  extent  in  this  zone  that  no  water  is  fed. 

Thus  we  have  a  means  whereby  the  fuel  mix- 
ture is  automatically  fed  under  governor  control 
in  correct  proportions  at  all  loads — the  water 
being  automatically  supplied  in  correct  propor- 
tions for  the  higher  loads  only  and  none  at  all 
being  admitted  for  the  light  loads. 

The  Secor-Higgins  carburetor  used  on  the 
18-35  and  30-60  Rumely  OilPull  sizes,  as  may 
be  seen  in  Figure  91,  is  divided  into  upper  and 
lower  sections,  the  upper  section  being  again 
divided  into  three  compartments.  The  compart- 
ment farthest  to  the  right  is  for  the  kerosene, 
the  middle  one  for  water  and  the  one  farthest 
to  the  left  for  gasoline.  All  open  into  the  lower 
section. 

The  lower  section  is  the  mixing  chamber.  In 
the  bottom  of  this  are  three  rectangular  open- 
ings. The  two  openings  on  the  left  hand  side 
admit  air  to  the  mixing  chamber;  the  one  on 


128 


Tractor  Engines. 


the  right  is  the  opening  to  the  manifold  through 
which  the  mixture  of  kerosene,  water  and  air 
passes  directly  into  the  cylinder.  A  plate  which 
is  controlled  by  the  governor  slides  back  and 
forth  over  these  openings.  The  openings  in  this 
plate  are  arranged  so  that  when  it  is  pulled  to 
the  right  the  outlet  to  ,the  cylinder  is  made 
smaller,  while  the  air  inlet  is  also  reduced  to  a 


Fig.    91.      Secor-Higgins    carburetor,    another   automatic    type 
used  by  Rumely. 

lesser  extent  through  the  uncovering  of  the  open- 
ing at  the  left  hand  of  plate/ 

Needle  valves  in  the  kerosene  and  water  cham- 
bers control  the  maximum  amount  of  fuel  and 
water  to  be  fed.  These  need  be  set  only  once 
at  full  load,  and  the  carburetor  under  governor 
control  then  takes  care  of  the  adjustment  for 
all  other  loads. 


About  the  Fuel  System.          129 

As  a  general  rule,  with  the  tractor  engine  the 
fuel  is  gravity  fed  from  the  tank  to  the  carbu- 
retor, the  tank  being  located  well  above  the  lever 
of  the  carburetor,  so  that  there  is  little  chance 
of  failure  even  when  the  machine  is  working 
on  a  steep  incline.  While  with  most  -tractors  of 
the  kerosene  burning  type  two  separate  tanks  are 
provided,  one  for  the  small  amount  of  gasoline 
needed  in  order  to  facilitate  starting  and  to  run 
the  engine  long  enough  to  warm  it  up  to  a  point 
where  it  will  handle  the  kerosene  fuel,  in  some 
instances,  as  for  instance  the  Case,  a  double 
compartment  tank  is  provided,  the  smaller  com- 

partment  being 
used  for  the 
gasoline.  The 
arrangement 
of  the  Case 
tank  is  made 
very  plain  by 
Figure  92. 
.  TO  CARBURETOR  Itwillbesccn 

Fig.  92.      Fuel  connections  and  strain-         that      the      COn- 
ers  on  Case  10-18. 

nections    are 

such  that  the  kerosene  can  be  shut  off  at  will  and 
the  engine  run  on  gasoline;  likewise  the  latter 
can  be  shut  off  and  the  engine  operated  on  the 
kerosene.  The  usual  practice  is  to  shut  off  the 
kerosene  and  switch  on  the  gasoline  a  few  mo- 
ments before  shutting  down  at  the  completion  of 
the  day's  work  so  that  the  gasoline  will  have,  a 
chance  to  fill  the  carburetor  bowl  in  preparation 
for  an  easy  start  next  morning. 

In  almost  every  instance  a  strainer  of  one  sort 
or  another  is  included  in  the  fuel  line  to  prevent 
passage  of  sediment  into  the  carburetor,  where  it 
is  bound  to  clog  up  the  nozzle  and  affect  the  run- 
ning of  the  engine.  The  arrangement  of  the  two 


130 


Tractor  Engines. 


strainers  on  the  Case  fuel  supply  line — one  for  the 
gasoline  tank  and  the  other  for  the  kerosene  tank 
— is  indicated  in  the  figure.  It  is  important  that 
they  be  cleaned  frequently. 

Carburetor  Adjustment. — The  proper  adjust- 
ment of  the  carburetor  is,  of  course,  a  matter 
which  will  have  to  be  determined  for  each  indi- 
vidual make  of  carburetor  and  engine  as  well. 
There  are  no  hard  and  fast  rules  for  effecting 
adjustment  which  will  fit  all  cases,  or  even  a 
majority  of  cases.  If  we  study  the  following 

principles,  however, 
we  will  find  that  they 
apply  to  all  carbure- 
tors, all  engines,  and 
all  fuels  common  to 
tractor  practice,  and 
will  aid  us  much  in 
carrying  out  the  terse 
directions  generally 
given  for  carburetor 
adjustment  in  the 
tractor  instruction 
book  furnished  by  the 
manufacturer. 

The  first  thing  to 
do,  in  attempting  to 
attain  the  adjustment 
of  any  carburetor 
wherein  the  fuel  supply  is  adjustable  by  means 
of  a  needle  valve,  is  to  bring  the  needle  valve 
gently,  but  fully,  to  its  seat  so  as  to  shut  off  all 
the  flow  through  the  jet  or  nozzle.  Care  should 
be  exercised  in  effecting  this,  not  to  jam  the  valve 
down  on  its  seat  and  cause  deformation  of  either 
the  needle  or  the  seat,  as  if  this  is  done  it  will 
be  almost  impossible  to  attain  a  correct  adjust- 
ment of  the  carburetor  without  replacing  the  parts 


Fig.  93.  Cross  section  of  pat- 
ented Mogul  mixer  and  cylinder, 
showing  adjustments. 


About  the  Fuel  System.          131 


with  new  and  perfect  ones.  Then  turn  the  needle 
back  one  or  two  turns — depending  on  the  carbu- 
retor and  the  size  of  the  engine — and  turn  the 
engine  over  to  start  it,  priming  the  cylinders  if 
necessary. 

Where  priming  is  not  necessary  it  will  be  well 
to  close  the  choke  valve  on  the  carburetor  to  pro- 
vide a  good  rich  mixture  for  starting.  With  the 
engine  running,  even  though  it  is  running  badly, 

do  not  attempt  to  ob- 
tain a  final  adjust- 
ment on  the  carbure- 
tor until  the  whole 
mechanism  has 
warmed  up.  Be  sure 
that  the  choke  valve 
is  opened  again  im- 
mediately after  the 
engine  has  started, 
for  if  it  is  held  closed 
the  over-rich  mixture 
supplied  will  choke 
the  engine  and  cause 
it  to  stop. 

After  thoroughly 
warming  up  the  en- 
gine, retard  the  spark 
fully  and  open  the 
throttle  sufficiently  to 
allow  the  governor  to 
control  the  engine  speed.  Then  adjust  the  needle 
valve  carefully,  first  to  limit  the  amount  of  gaso- 
line supplied,  noting  the  effect  on  the  operation 
of  the  engine.  Continue  until  the  speed  begins 
to  fafl  off,  and  then  turn  the  other  way  until  the 
smoothest  possible  running  is  obtained. 

Now  close  the  throttle,  and  advance  the  spark 
quarter  way.     The  engine  should  run  evenly  and 


Fig.  94.  View  of  Verosene 
mixer  and  water  injector,  show- 
ing adjusting  devices. 


132  Tractor  Engines. 


at  low  speed,  well  throttled  down.  The  speed 
can  be  regulated  by  resetting  the  stop  screw  on 
the  throttle  lever. 

If  the  engine  shows  a  tendency  to  backfire  or 
"pop"  in  the  carburetor  when  the  throttle  is 
opened  quickly,  it  is  evidence  of  a  lean  mixture, 
which  should  be  corrected  by  opening  the  needle 
valve  very  slightly  until  this  tendency  is  no  longer 
apparent. 

If  the  engine  is  hard  to  start  and  will  not  idle, 
or  knocks  as  if  afflicted  with  carbon  or  spark 
knock  when  the  throttle  is  opened  quickly,  it  is 
further  evidence  of  lean  mixture  and  should  be 
corrected  by  opening  the  needle  valve  adjustment 
slightly.  Rich  mixture  will  make  itself  apparent 
by  fhe  presence  of  black  smoke  issuing  from  the 
exhaust,  which  is  characterized  by  a  pungent 
odor,  unmistakable  to  the  trained  engine  oper- 
ator. Blue  smoke,  on  the  other  hand,  has  noth- 
ing whatever  to  do  with  the  carburetor  adjust- 
ment, resulting  solely  from  an  overabundance 
of  lubricating  oil.  Likewise  a  white  haze  issuing 
from  the  exhaust,  in  the  case  of  a  kerosene- 
burning  engine,  indicates  that  the  supply  of  water 
through  the  injector  is  slightly  too  much  for  the 
amount  of  fuel  being  burned  and  the  load  being 
carried,  and  the  water  supply  should  be  cut  down 
slightly. 

Further  evidence  of  a  -rich  mixture  is  sluggish 
action  of  the  engine,  which  sometimes  is  accom- 
panied by  a  heavy  pound  which  is  quite  irregular 
and  which,  therefore,  can  readily  be  distinguished 
from  a  bearing  knock ;  and  by  a  marked  tendency 
for  the  engine  to  overheat,  causing  boiling  away 
of  the  cooling  water.  The  best  way  to  verify  the 
conclusion  that  the  mixture  is  over-rich  is  to 
turn  off  the  fuel  with  the  throttle  set  to  produce 
an  engine  speed  slightly  under  the  governed 


About  the  Fuel  System.          133 

speed  of  the  engine ;  if  the  engine  picks  up  speed 
after  a  minute  or  two,  due  to  lowering  of  the 
fuel  level  in  the  carburetor  and  consequent  weak- 
ening of  the  mixture,  it  is  evident  that  the  mix- 
ture has  been  too  rich,  and  correction  should 
be  made  by  closing  the  needle  valve  slightly  to 
provide  good  operation  as  outlined  in  the  tests 
above. 

Repairs. — If  it  is  found  impossible  to  obtain  a 
satisfactory  setting  of  the  carburetor,  it  is  likely 
that  the  device  is  out  of  order 
and  in  need  of  some  slight  re- 
pairs. The  first  thing  to  look 
for  is  correctness  of  the  fuel 
level.  In  most  tractor  carbure- 
tors the  fuel  level  is  correct 
when  the  fuel  just  rises  enough 


1- GALLON 
OILCAN 


nG.95 

Fig.   95.      Simple   means   of   determining  the   correct  adjustment 
of  the  float  in  the  carburetor. 

to  overflow  the  shoulder  surrounding  the  nozzle 
in  the  mixing  chamber  so  that  ^he  well  is  full  of 
fuel  for  starting.  If  the  level  does  not  reach  this 
point,  hard  starting  and  the  inability  of  the  en- 
gine to  idle  will  be  the  result  due  to  weak  mix- 
ture. The  float  lever  should  be  bent  very 
slightly  and  the  carburetor  tested  to  see  if  the 
correct  level  has  been  attained ;  this  may  have  to 
be  repeated  several  times  in  order  to  effect  a  cure. 
Figure  95  shows  a  hook  up  for  tesjting  the  level. 
If  the  fuel  level  is  much  above  this  point,  we 
will  have  a  sluggish  engine  due  to  rich  mixture. 
It  may  be  caused  either  by  wear  of  the  gasoline 


134  Tractor  Engines. 


inlet  valve  pin  or  its  seat,  causing  leakage,  so 
that  the  operation  of  the  float  does  not  stop  the 
flow  of  gasoline  into  the  carburetor  bowl.  The 
correction  is  to  fit  new  valve  needle  and  seat  and 
so  adjust  with  the  float  as  to  permit  of  the  cor- 
rect fuel  level  being  attained.  A  bit  of  dirt  on 
the  valve  seat  will  have  the  same  effect.  The 
float  may  have  become  "water-logged" ;  that  is, 
it  may  have  absorbed  so  much  of  the  fuel  that 
it  has  lost  some  of  its  buoyancy  and  will  no 
longer  close  the  valve  fully.  In  this  case  replace- 
meet  with  a  new  float  affords  the  best  cure,  and 
care  should  be  taken  to  see  to  it  that  the  float 
is  coated  with  shellac  varnish  (except  where 
alcohol  is  used  as  fuel)  to  protect  it  from  the 
action  of  the  fuel  causing  a  repetition  of  the 
trouble. 

The  adjustment  of  the  float  operating  lever 
may  be  such  that  it  does  not  close  the  needle 
valve  quickly  enough  so  that  a  higher  level  than 
correct  is  attained.  Correction  is  made  by  bend- 
ing the  lever  away  from  the  float  slightly  to 
permit  earlier  closing  of  the  needle  valve. 

The  carburetor  may  have  dirt  or  grit  in  it 
which  will  stop  up  the  jet  or  nozzle,  retarding 
the  fuel  flow,  or  it  may  have  a  drop  or  two  of 
water,  which  will  have  the  same  effect.  In  this 
case  it  is  well  to  take  the  carburetor  off  and 
clean  it  thoroughly.  Then  remove  the  gas  line 
from  the  tank  and  blow  through  it  to  clean  out 
thoroughly,  making  sure  at  the  same  time  that 
the  sediment  bulb  is  clean  and  free  from  water. 
To  prevent  recurrence  of  the  trouble,  drain  a 
teacupful  of  gasoline  from  the  sediment  bulb  on 
the  tank  frequently  to  prevent  dirt  from  reaching 
the  carburetor,  and  at  least  once  a  week  drain 
the  carburetor  by  means  of  drain  cock  provided 
on  bottom  of  the  bowl;  this  will  wash  it  out 


About  the  Fuel  System.          135 

thoroughly  and  eliminate  any  sediment  or  water 
which  has  escaped  through  the  sediment  bulb  and 
strainer  provided  on  the  bottom  of  the  fuel  tank. 

Wear  of  the  needle  valve  and  its  seat  will  re- 
sult in  a  condition  where  it  is  no  longer  possible 
to  obtain  a  correct  carburetor  adjustment.  In 
such  a  case,  the  proper  thing  to  do  is  to  replace 
the  worn  parts  with  new  ones.  Likewise  wear 
of  the  throttle  disc  will  prevent  idling  of  the 
engine  unless  the  mixture  is  altogether  too  rich 
for  good  operation  under  full  load  conditions. 
The  disc  clearance  should  be  about  .008  of  an 
inch  with  the  disc  closed;  if  it  is  appreciably 
more  than  that,  replace  it  with  a  new  disc.  The 
clearance  of  the  throttle  spindle  should  be  no 
more  than  .005  of  an  inch;  where  it  is  greater 
it  will  permit  of  air  leaking  in  to  thin  the  mix- 
ture, producing  irregular  operation  and  inability 
to  throttle  the  engine  down.  This  is  also  the 
case  if  any  of  the  joints  of  the  intake  manifold 
or  intake  piping  are  not  tight;  there  are  several 
of  them  in  some  instances.  In  most  cases  they 
are  made  tight  with  copper  asbestos  gaskets. 

To  detect  leakage  at  these  points,  start  the  en- 
gine and  have  it  running  with  the  throttle  closed 
as  far  as  possible.  Squirt  lubricating  oil  from  a 
hand  oil  can  around  the  joint.  In  case  of  leak- 
age, the  oil  will  be  sucked  into  the  manifold  at 
the  place  where  such  leakage  occurs.  Correction 
can  be  made  by  tightening  the  hold-down  nuts 
by  means  of  which  the  manifolds  are  held  in 
place,  or  in  the  case  of  a  bad  leak,  by  replacing 
the  gaskets  with  new  ones  and  setting  the  hold- 
down  nuts  up  tight. 

Doubtless  it  will  prove  helpful  to  the  oper- 
ator, regardless  of  the  make  of  machine,  to  digest 
the  following  complete  instructions  for  the  care 
of  the  fuel  system,  which  have  been  prepared 


136  Tractor  Engines. 

to  cover  the  Twin  City  line,  which  is  one  of  many 
equipped  with  the  Bennett  carburetor: 

Fuel  from  the  small  gasoline  tank  flows  to 
the  carburetor  by  gravity. 

Fuel  after  being  placed  in  the  main  supply  tank 
is  pumped  from  there  to  the  overflow  cup,  above 
the  motor,  and  flows  from  the  cup  to  the  motor 
by  gravity.  After  switching  to  the  main  supply 
tank,  if  the  pump  does  not  bring  fuel  to  the 
overflow  cup,  look  for  the  following  causes: 

Empty  supply  tank. 

Leak  in  pipe  between  pump  and  tank. 

Dirt  under  check  valves. 

Pump  needs  repacking. 

A  fuel  strainer  is  placed  in  the  pipe  line 
where  it  joins  the  carburetor.  This  should  be 
opened  occasionally  and  the  dirt,  if  any,  removed. 

There  are  two  check  valves  located  in  the  line 
leading  from  the  fuel  tank  to  the  pump,  and  in 
case  of  trouble  these  should  be  examined. 

If  the  pump  gradually  fails  to  pump  and  dis- 
charges a  stream  of  bubbles  into  the  overflow 
cup,  it  indicates  that  there  is  a  leak  in  the  pipe 
line  between  the  pump  and  the  tank,  or  that  the 
tank  is  empty. 

Leaks  in  the  pipe  line  are  easily  caused  by 
fittings  working  loose,  and  in  such  a  case  they 
should  be  unscrewed  and  the  threads  covered 
with  shellac  or  common  laundry  soap;  then  re- 
assemble. Care,  should  be  taken  not  to  strain 
valves  or  checks  in  screwing  them  together. 

In  case  the  pump  is  not  working  tighten  the 
gland  which  forces  the  packing  around  the 
plunger.  Never  use  any  sticky  or  gritty  material 
for  packing.  Drop  a  little  lubricating  oil  around 
the  plunger  after  the  gland  is  tightened.  Do  not 
force  this  gland  too  tight  or  it  will  bind  the 
plunger  and  break  the  pump  from  its  fastenings. 


About  the  Fuel  System.          137 

If  the  fuel  leaks  around  the  pump  plunger,  the 
pump  should  be  repacked.  In  placing  the  new 
packing,  unscrew  the  cap,  lift  the  gland  out  of 
the  pump  barrel  and  remove  all  the  old  packing, 
replacing  it  with  new.  Common  laundry  soap  is 
a  good  lubricant  for  this  purpose,  and  it  is  well 
to  mix  a  little  of  it  with  the  new  packing.  After 
rep^cing  the  gland,  screw  the  cap  down  fairly 
tight;  then  loosen  it  until  you  are  sure  the  pump 
plunger  works  freely. 

A  good  method  of  packing  the  pump  is  to 
make  two  rings  of  No.  315  3/16-inch  Anchor 
brand  braided  packing  and  place  in  the  packing 
space  and  fill  up  the  rest  with  lamp-wicking. 

The  fuel  supply  must  be  kept  .clean.  If  the 
pump  suddenly  starts  and  then  stops  pumping, 
it  indicates  that  there  is  dirt  coming  through  the 
check  valves.  Any  dirt  that  happens  to  get  into 
the  fuel  tank  is  liable  to  be  drawn  up  into  the 
check  valves  or  carburetor  and  cause  trouble. 
To  prevent  dirt  or  water  from  getting  into  the 
fuel,  it  should  be  filtered  through  chamois  skin, 
or,  in  any  case,  should  be  strained  through  a  fine 
screen. 

If  there  is  plenty  of  fuel  in  the  overflow  cup 
and  the  engine  misses,  first  throwing  out  black 
smoke  when  the  needle  valve  is  opened  far 
euough  so  that  it  will  run  at  all,  and  then  pop- 
ping back  through  the  carburetor,  and  no  ad- 
justment of  the  fuel  valve  will  stop  it,  the  indi- 
cations are  that  there  is  dirt  in  the  pipe  leading 
from  the  overflow  cups  to  carburetor,  which  has 
clogged  the  needle  valve  or  supply  pipe,  so  that 
the  fuel  does  not  flow  into  the  carburetor  fast 
enough  to  keep  up  the  supply.  Dirt  may  also 
lodge  in  the  carburetor  float  valve.  This  usu- 
ally causes  the  carburetor  to  overflow  and  drip 
from  the  bottom.  The  only  remedy  for  this 


138 


Tractor  Engines. 


Fig.  96.  Shows  the 
enclosed  type  of  Ben- 
nett carburetor  as 
used  on  the  Twin  City 
motors. 


is  to   take  the  pipes   and  carburetor  apart  an 
clean  them. 

If  the  exhaust  has  a  weak  muffled  sound,  and 
shows  black  smoke,  too  much 
fuel  is  being  fed  through  the 
carburetor.  If  it  back-fires  or 
coughs  back  through  the  car- 
buretor, the  mixture  is  not 
rich  enough  and  needs  more 
fuel. 

To  adjust  the  enclosed  type 
Bennett  carburetor  (Fig.  96). 
Turn  fuel  needle  "A"  clock- 
wise as  far  as  possible,  and 
then  unscrew  about  one  full 
turn.  Start  motor,  and  by 
screwing  air  valve  "B"  clock- 
wise, let  as  much  air  in  as 
possible  without  making  the 

motor  miss  or  backfire.  Do 
not  open  water  needle  "D" 
unless  engine  is  using  kero- 
sene. 

To    adjust    the    open    type 
Bennett  carburetor  (Fig.  97). 
Open  fuel  needle  two  full 
turns,  and  when  motor  is  run- 
ning cut  down  to   iy2   turns. 
It   will    not   be    necessary    to 
touch   the   air    valve,    but    in 
case  the  motor  smokes  too 
Fig.  97.    shows  the    much    and    the    fuel    is    cut 
open  type  as  used  on    down  to  good  running:,  loosen 

all  Twin    City  motors  «/— ,,  , 

except  the  4^x7  size,    nut      L      and    use    a    screw- 
driver    to    turn    screw    "B" 
clockwise.     This  will  supply  more  air. 

It  may  be  necessary  to  give  a  little  more  fuel, 
but  for  best  economy  the  carburetor  should  be 


About  the  Fuel  System.          139 

adjusted  to  use  as  little   fuel  and  as  much  air 
as  possible. 

To  USE  KEROSENE  AS  FUEL. 

There  are  two  fuel  tanks  used  in  the  opera- 
tion of  Twin  City  Motors. 

One  is  a  small  tank  for  gasoline,  mounted 
higher  than  the  motor  from  which  the  fuel  flows 
by  gravity  to  the  carburetor,  and  the  other  is  a 
large  tank  from  which  the  fuel  is  pumped  to  a 
glass  overflow  cup  and  thence  flows  to  the  car- 
buretor by  gravity. 

The  engine  must  be  started  on  gasoline.  After 
the  bowl  of  the  carburetor  is  hot,  shut  off  the 
gasoline  and  turn  kerosene  into  the  carburetor. 

After  the  kerosene  starts  into  the  engine,  it  will 
sputter  and  choke,  and  the  fuel  needle  valve  will 
have  to  be  opened  one-quarter  turn  on  the  open 
type,  and  one  full  turn  on  the  enclosed  type. 

After  the  engine  runs  a  little  there  may  be 
heard  a  metallic  knocking  or  pounding,  which  is 
caused  by  preignition.  In  order  to  eliminate  this 
the  water  injector  valve  should  be  opened  and 
a  little  water  sprayed  into  the  intake  pipe.  This 
will  cut  down  the  heat,  and  the  knocking  will 
cease. 

It  will  be  necessary  to  retard  the  spark  from 
that  used  for  gasoline. 

The  engine  will  operate  best  on  kerosene  when 
the  least  possible  water  is  injected.  Just  keep 
the  adjustment  so  that  the  engine  will  not  knock. 

It  is  advisable  to  shift  the  carburetor  back  on 
to  gasoline  when  the  motor  is  idle  a  great  deal, 
as  the  bowl  of  the  carburetor  will  not  continue 
to  be  hot  unless  some  load  is  kept  on  the  engine. 

Caution. — Be  sure  and  turn  off  water  valve 
when  engine  is  not  running. 

It  is  a  good  plan  to  shut  off  both  fuel  pipes, 


140  Tractor  Engines. 

drain  carburetor,  and  leave  drain  open  when 
the  engine  is  not  running,  as  this  gives  the 
float  a  chance  to  dry  out  and  prevents  water 
getting  into  the  fuel,  if  the  water  valve  should 
be  left  or  leaks. 

The  hot  air  jacket  around  the  bowl  of  the 
carburetor  must  be  kept  clean,  as  the  successful 
operation  of  the  carburetor  depends  upon  this. 

ALCOHOL. 

The  use  of  alcohol  as  a  fuel  for  the  internal 
combustion  engines  is  very  clean  and  no  carbon 
whatever  is  caused  from  it.  If  a  carbon  deposit 
forms  in  the  combustion  chamber,  it  is  from 
using  too  much  lubricating  oil  and  not  from  the 
alcohol. 

All  that  is  necessary  to  equip  Twin  City  motors 
to  burn  alcohol,  is  to  raise  the  compression  of 
the  motor  by  putting  in  longer  pistons,  and  to 
replace  the  carburetor  float  with  another  which 
has  a  specially  prepared  coating  instead  of  the 
shellac. 

Gasoline  is  used  to  start  the  motor,  but  after 
the  bowl  of  the  carburetor  is  warmed  up,  alcohol 
can  be  used. 

From  eight  to  nine  per  cent  more  power  can 
be  obtained  with  alcohol  than  with  gasoline,  al- 
though about  eleven  per  cent  more  alcohol  will 
be  used  than  kerosene,  and  thirty-eight  per  cent 
more  than  gasoline,  for  the  same  load.  That  is, 
it  will  take  4.8  gallons  of  gasoline,  6  gallons 
of  kerosene  or  6.7  gallons  of  alcohol  for  the 
same  time  and  load. 

The  better  the  .grade  of  alcohol,  the  less  it  will 
take  and  the  economy  in  the  use  of  one  grade 
over  the  other  will  be  all  the  way  up  to  ten  per 
cent.  • 


About  the  Fuel  System.          141 

The  gravity  of  a  good  grade  of  denatured 
alcohol  is  .809,  which  is  7^.  pounds  to  the  gallon, 
about  the  same  as  kerosene. 

NAPHTHA. 

Naphtha  is  used  in  the  same  way  as  kerosene, 
but  the  amount  used  will  be  a  little  more  than 
gasoline  and  a  little  less  than  kerosene  for  the 
same  load, — that  is,  .4.8  gallons  of  gasoline,  5.18 
gallons  of  naphtha  or  6  gallons  of  kerosene  for 
the  same  full  load  for  the  same  unit  of  time. 

A  COMPARISON  OF  FUELS. 
A  comparison  of  fuel  consumption  of  various 
fuels,   when  the   engine   is   working   under   full 
load,  is  given  in  the  table  below,  taking  gasoline 
as  1.  Specific 

Gals.          Gravity 

Gasoline  1.00  .7449 

Naphtha 1.07  .7639 

Kerosene   1.24  .8098 

Alcohol    1-.38  .809 

INSTRUCTIONS    FOR    BURNING    KEROSENE    WITH 
CLAPPER  VAPORIZER,  USED  ON  BULL  TRAC- 
TOR (FIGURE  98— A-B-C.) 

Always  start  the  motor  on  gasoline  and  adjust 
the  needle  valve  in  carburetor  to  handle  the  full 
load  as  though  you  intended  to  run  on  gasoline, 
and  as  soon  as  the  vaporizer  chamber  is  warmed 
from  the  exhaust,  switch  from  gasoline  to  kero- 
sene. There  is  no  other  adjustment  necessary. 
In  working  the  motor  to  its  maximum  capacity, 
it  may  be  necessary  to  open  the  needle  valve  in 
carburetor  about  one-quarter  turn,  which  you 
would  necessarily  have  to  do  with  easoline. 

With  the  use  of  kerosene  in  extreme  loads, 
or  when  there  is  a  "metallic  click"  in  cylinder, 
use  a  small  amount  of  water,  the  amount  vary- 


142  Tractor  Engines. 

CLAPPER  KEROSENE  VAPORIZER. 


Plate   No.    1. 

No.  1 — Water  spray  valve. 

No.   2 — 3-way  valve. 

No.  3 — Carburetor  drain. 

No.  4 — Carburetor  needle  valve. 
Single  adjustment  for  kerosene  the 
same  as  gasoline. 


Plate  No.  2. 

Side  view  of  Clapper  Kerosene 
Vaporizer  showing  simplicity  of  con- 
struction. Positively  no  moving  parts. 
Unquestionably  the  greatest  improve- 
ment of  the  age  for  the  successful 
burning  of  kerosene. 


If  motor  stops  when 
burning  kerosene  and 
stands  for  any  length 
of  time,  switch  3-way 
valve  on  to  gasoline 
and  open  pet-cock  (No. 
3,  Plate  1)  to  drain  off 
the  kerosene.  Prime 
cylinders  before  again 
trying  to  start. 

Operate  tractor  under 
load  at  least  five  min- 
utes before  attempting 
to  switch  \o  kerosene. 


Plate  No.  3. 

Always  keep  glass  jar 
in  place.  Empty  out  as 
often  as  necessary  (No. 
2,  Plate  3). 

To  fill  oil  reservoir, 
remove  plug  in  filling 
pipe  (No.  1  in  Plate  3). 
Fill  to  within  three 
inches  of  top.  Be  sure 
to  screw  plug  in  tight 
to  avoid  sucking  air. 


Fig.  98.     Showing  in  detail  the  adjustments  necessary. 


About  the  Fuel  System.          143 

ing  to  the  load.  When  running  idle  or  you  stop 
the  motor,  always  shut  off  the  water.  It  is  ad- 
visable to  shut  off  the  kerosene  line  before  you 
stop  the  motor  to  allow  the  carburetor  to  fill  up 
with  gasoline  ready  for  starting  again. 

You  will  get  more  power  and  better  results 
with  a  retarding  spark  on  kerosene  than  gasoline, 
due  to  the  perfect  vapor  and  more  heat  units — 
simply  pnll  magneto  spark  control  rod  back  until, 
from  the  sound  and  power  developed,  you  have 
the  proper  range  for  igniting  the  charge. 


Fig.  99.     Adjusting  leaky  carburetor. 

A  leaky  carburetor  is  the  result  of  dirt  in  the 
inlet  valve,  preventing  the  float  needle  from 
seating  properly. 

To  remove  this,  remove  plug  from  over  the  float 
needle  (Fig.  99)  and  work  the  needle  in  the  inlet 
valve  up  and  down  several  times,  pressing  it 
to  its  seat  each  time  and  turning  it.  This  will 
remove  any  foreign  matter  that  may  have  gath- 
ered there  and  allow  the  float  needle  to  seat  itself. 

If  this  does  not  stop  the  leak,  float  is  too  high 
and  should  be  set  lower. 


144  Tractor  Engines. 


Once  a  season,  the  float  should  have  a  coat 
of  shellac.  It  will  take  but  a  moment,  as  it  dries 
very  rapidly.  (Have  float  dry  before  putting 
on  shellac.) 

There  may  be  sediment  in  the  bottom  of  the 
bowl  of  the  carburetor.  Remove  the  bowl  and 
clean  it  out. 

One  of  the  most  important  points  in  connec- 
tion with  the  operation  of  the  tractor  ^engine  is 
to  keep  grit  and  dust  from  reaching  the  bear- 
ing surfaces,  such,  for  instance,  as  the  cylinder 
walls,  main  and  connecting  rod  bearings,  etc.  It 
is  obvious  that  any  dirt  carried  in  through  the 
air  inlet  on  the  carburetor  will  be  brought  into 
direct  contact  with  the  cylinder  walls,  which 
are,  of  course,  covered  with  a  layer  of  oil  suffi- 
ciently "tacky"  to  catch  the  grit  and  hold  it. 
Rapid  wear  of  the  wall  surfaces  can,  therefore, 
be  expected. 

But  more  than  this — the  oil  from  the  cylinder 
walls  is  carried  down,  in  part,  by  the  downward 
movement  of  the  piston  and  a  generous  measure 
of  the  grit  reaches  the  crankcase  chamber  where, 
in  the  case  of  the  engine  equipped  with  a  circu- 
lating lubricating  system,  it  will  enter  the  oil 
supply  to  be  circulated,  and  recirculated,  to  the 
engine  bearing  surfaces. 

It  is  only  to  be  expected,  therefore,  that  an 
engine  not  protected  in  the  best  possible  manner 
from  the  entrance  of  grit,  as  above  pointed  out, 
will  wear  out  more  quickly  and  give  far  greater 
trouble,  calling  for  frequent  repairs,  than  one 
adequately  protected  from  such  dust.  There  are 
very  few  tractors  now  on  the  market,  therefore, 
on  which  the  engines  .are  not  equipped  with  some 
device  for  freeing  the  air  entering  the  carbu- 
retor from  contamination  so  that  nothing  but 
pure,  clear  air  is  taken  into  the  cylinders. 


oat 

'1P»C 


About  the  Fuel  System.          145 

These  air  filters  or  air  washers,  as  they  are 
variously  called,  are  built  to  operate  .on  three 
distinct  principles.  The  simplest  is  nothing  more 
nor  less  than  a  filter,  all  the  air  entering  the  cyl- 
inder being  caused  to  pass  first  through  a  filter- 
ing medium  such  as  a  piece  of  felt  cloth  by 
means  of  which  the  dust  is  eliminated.  Perhaps 
the  best-known  device  of  this  sort  is  the  Orem 
motor  protector,  in  which  the  filtering  felt  is 
stretched  over  the  surface  of  a  wire  netting  cyl- 
inder from  the  interior  of  which  air  for  the 
carburetor  supply  is  drawn;  all  the  air  reaching 
the  interior  must  pass  through  the  cloth. 

It  is  evident  that  strangulation  of  the  air,  or 
any  impediment  to  its  free  entry  into  the  carbu- 
retor, will  result  in  a  falling  off  in  power ;  as 
the  filter  cloth  does  offer  some  resistance,  its 
area  must  be  made  sufficient  to  cut  this  resist- 
ance to  a  minimum.  In  the  Orem  device,  this 
area  has  been  figured  with  relation  to  the  amount 
of  air  a  given  engine  will  handle  in  a  minute, 
under  full  load  operation. 

Furthermore,  unless  some  means  were  taken 
to  prevent  such  action,  after  a  few  moments  of 
operation  under  extreme  dust  conditions,  the 
filter  cloth  would  become  so  clogged  as  to  par- 
tially strangle  the  air  passage.  In  the  Orem 
device  this  is  prevented  by  the  simple  expedient 
of  setting  the  cylinder  upright,  or  in  a  vertical 
position,  whereby  the  vibration  of  the  engine 
itself  is  employed  to  cause  the  dust  to  drop  off 
the  outside  surface  of  the  filter  cloth  into  a  col- 
lecting funnel,  from  which  it  can  be  emptied 
from  time  to  time  as  occasion  demands.  The 
device  also  serves  as  a  regulator  for  the  tem- 
perature of  the  incoming  air.  This  is  effected 
•by  connecting  the  outer  cylinder  to  the  air  stove 
on  the  exhaust  pipe  whereby  heated  air  is  brought 


146 


Tractor  Engines. 


to  the  device.  A  regulating  shutter  is  provided, 
however,  so  that  cold  air  can  be  introduced  to 
bring  down  the  temperature  of  this  air  during 
the  hot  summer  months  when  particularly  high 
heat  is  not  required. 

The  second  type  separates  the  dust  from  the 
air  on  the  centrifugal  principle.  The  entering 
air  is  caused  to  take  up  a  very  rapid  swirling 
or  rotary  motion  by  the  form  of  the  passageway 
into  the  cleaner;  due  to  their  great  weight  in 
comparison  with  the  weight  of  the  air  itself,  the 
dust  particles  are  thrown  to  the  outer  wall  of 

the  case,  where  they 
are  caused  to  settle 
out  by  gravity.  The 
well  -  clean-sed  air  is 
drawn  from  the  cen- 
ter of  the  device,  a 
point  which  the  heavy 
dust  particles  cannot 
reach  because  of  the 
effect  of  the  centri- 
fugal force  acting  on 
them  due  to  their 
rapid  circular  motion. 
By  far  the  most 
popular  type  of 
cleaner,  however,  is 
the  air  washer,  one  of 
which  is  shown  in  the 

accompanying  illustration  (Fig.  100).  In  this 
type  all  the  entering  air  is  caused  to  bubble  up 
through  a  quantity  of  water,  which  collects  the 
dust  and  dirt  and  leaves  the  air  absolutely  clean. 
Perhaps  the  effectiveness  of  the  device  as  an  air 
cleaner  is  only  partially  responsible  for  the  popu- 
larity of  the  air  washer;  the  other  big  point  in 
its  favor  is  the  fact  that  it  humidifies  the  enter- 


Fig.    100.      A    typical   tractor 
air  washer. 


About  the  Fuel  System.          147 

ing  air  and  acts,  to  a  certain  extent,  to  smooth 
out  the  action  of  the  engine  and  eliminate  the 
formation  of  carbon  deposit. 

A  sectional  view  of  a  typical  air  washer  such 
as  is  fitted  to  the  popular  Case  tractor  is  given 
in  Figure  100.  It  comprises  a  cylindrical  vessel 
partially  filled  with  water,  the  level  being  indi- 
cated by  a  glass  sight  on  one  side  of  the  casing. 
The  air  enters  through  a  central  pipe  running 
about  half  way  up  into  the  chamber;  but  the  air 
finds  itself,  not  in  the  housing,  but  in  a  smaller 
inverted  cylinder  placed  over  the  air  intake  pipe. 
This  second  or  inner  chamber  is  attached  to  a 
metal  float  which  rises  and  falls  with  the  water 
level  in  the  air  washer,  and  the  only  passage 
for  the  air  out  of  the  chamber  is  past  the  bottom 
of  the  inverted  cup,  over  the  lower  surface  of 
the  float  and  up  along  the  sides.  The  top  of  the 
air  washej  housing  is  attached  to  ,the  carburetor 
air  intake,  so  that  immediately  the  engine  is 
turned  over,  some  of  the  air  is  exhausted,  and 
we  have  a  partial  vacuum  formed  sufficient  to 
cause  the  air  to  bubble  through  the  water,  finding 
its  way  from  the  inner  to  the  outer  compartment ; 
and  in  passing  through  the  water  it  is  freed  of 
its  dust  and  dirt. 

The  arrangement  of  the  inner  chamber  on  a 
float  is  a  very  simple  means  of  insuring  that  the 
air  must  pass  through  a  given  depth  of  water, 
regardless  of  the  quantity  of  water  in  the  air 
washer.  In  6ther  words,  provided  that  the  water 
level  is  maintained  so  that  it  can  be  seen  through 
the  sight  gauge,  the  suction  necessary  to  draw 
the  air  through  the  air  washer  will  always  be 
the  same.  The  level  of  the  water  cannot  be 
brought  too  high,  for  if  it  should  be  brought 
above  the  air  intake  pipe,  it  simply  will  overflow 
and  run  off;  it  should  never  be  allowed  to  evap- 


148  Tractor  Engines. 

orate  to  a  point  where  the  level  cannot  be  seen 
in  the  sight  gauge,  however,  as  then  the  desirable 
features  of  the  device  are  impaired  and  dirt  will 
be  carried  into  the  engine  cylinders. 

It  is  well  to  remove  the  drain  plug  from  the 
bottom  of  the  device  frequently  and  wash  out 
the  sediment  that  has  collected.  The  best  plan 
is  to  fill  the  washer  to  capacity  with  clean  water 
every  day,  making  sure  that  the  water  filler  plug 
on  top  of  the  device  is  replaced  tightly.  If  the 
plug  is  not  replaced,  the  washer  might  just  as 
well  be  off  the  engine  for  all  the  good  it  will  do. 

In  the  case  of  the  dry  types  of  air  cleaners, 
it  is  well  to  bear  in  min4  that  cleaning  the  sedi- 
ment trap  should  never  be  attempted  with  the 
engine  running.  To  do  so  means  that  the  dirt 
stirred  up  in  the  process  will  be  drawn  in  large 
quantities  into  the  cylinders  to  the  detriment  of 
the  engine. 


CHAPTER  VI. 

Lubrication  of  the  Engine. 

Why  One  Oil  Will  Not  Do  for  All  Types.   Factors 
Affecting  the  Oil  Used. 

BETWEEN  tractor  success  and  tractor  fail- 
ure ;  between  a  farm  power  machine  which 
runs  well  and  delivers  its  power  smoothly,  eco- 
nomically and  reliably  and  one  which  is  spas- 
modic in  its  performance,  unable  to  stand  up  to 
its'  work,  unreliable  and  troublesome,  there  lies 
a  very  narrow  chasm — a  film  of  oil  perhaps  .003 
of  an  inch  in  thickness,  sometimes  more  and 
oftentimes  considerably  less. 

This  oil  film,  quite  regardless  of  the  amount  of 
work  or  kind  of  work  the  tractor  is  called  upon 
to  do,  regardless  also  of  temperature  conditions 
both  inside  and  outside  the  engine ;  and  notwith- 
standing other  operative  conditions  which  may 
tend,  at  times,  to  destroy  it,  must  be  maintained 
religiously.  Even  momentary  failure  of  the  oil 
film  at  any  one  of  a  score  of  vital  points  in  the 
power  plant  will  mean:  first,  k/ss  of  power  out- 
put and  irregular  operation ;  second,  and  even 
more  annoying,  excessive  wear;  eventual  break- 
down and  stoppage ;  troublesome  and  costly 
repairs. 

Broadly  speaking,  the  oil  film  serves  the  same 
purpose  in  a  plain  bearing  as  do  the  steel  balls 
in  the  ball-type  anti-friction  bearing.  It  separ- 
ates the  rubbing  surfaces,  keeping  them  out  of 
actual  metallic  contact  and  replaces  the  rubbing 
friction,  which  otherwise  would  be  set  up  be- 
tween the  metal  surfaces  in  contact,  with  greatly 
lessened  friction  between  the  liquid  particles 

(149) 


150 


Tractor  Engines. 


themselves  and  between  the  liquid  particles  and 
the  metallic  surfaces  of  the  bearings,  just  as  in 
the  ball  or  roller  bearing  the  greatly  lessened 
rolling  friction  between  the  balls  or  rollers  and 
the  raceways  is  substituted  for  the  rubbing  fric- 
tion of  the  plain  bearing  surfaces. 

Points  in  the  engine  (Figure  101)  at  which  it 


Fig.    101.     Section    through    typical    tractor    engine,    showing 
points  where  oil  is  necessary. 

is  essential  that  this  oil  film  be  maintained  for 
the  purpose  of  reducing  friction,  and  the  power 
loss  and  wear  which  it  entails,  are  the  mainshaft, 
crankpin,  piston  pin  and  camshaft  bearings ;  the 
cylinder  walls  for  lubrication  of  the  cylinders 
themselves,  the  pistons  and  piston  rings ;  the 
cams,  cam  followers  and  cam  follower  guides; 
the  timing  gear  mesh  and,  where  used,  the  tim- 
ing gear  idler  wheel  bearing. 


Lubrication  of  the  Engine.        151 

Wholly  aside  from  its  function  of  reducing 
sliding  friction  between  the  piston  and  the  cylin- 
der wall,  the  oil  film  on  the  latter  performs  an- 
other and  a  highly  important  service.  Expand- 
ing packing  rings,  called  piston  rings,  are  fitted 
to  the  pistons  as  a  means  of  filling  the  clearance 
space  which  must  be  left  between  the  piston  and 
cylinder  walls  in  order  to  provide  room  for  ex- 
cess expansion  of  the  piston  over  and  above  the 
increase  in  diameter  of  the  cylinder  bore  due  to 
the  fact  that  the  piston  operates  normally  at 
considerably  higher  temperature  than  the  cylin- 
der walls. 

This  will  readily  be  appreciated  when  it  is 
considered  that  the  cylinder  walls  themselves 
are  directly  cooled  by  the  water  circulating  sys- 
tem, whereas  the  head  of  the  piston  is  cooled 
only  by  means  of  heat  being  conducted  to  the 
piston  skirt  and  transferred  from  that  point 
through  the  oil  film  to  the  cylinder  walls  for  ab- 
sorption by  the  cooling  medium.  These  rings, 
which  are  applied  to  the  piston,  must  be  so  fitted 
as  to  leave  a  working  clearance  in  the  ring  slot; 
were  this  not  the  case  they  would  be  likely  to 
stick  in  the  ring  slot,  preventing  their  expansion 
against  the  cylinder  walls  and  thereby  defeating 
their  own  purpose. 

Rings,  for  the  most  part,  are  eccentric  in 
form;  that  is,  the  outer  or  bearing  surface  is  not 
struck  from  the  same  center  as  the  inner  circle. 
The  slot  or  joint  is  formed  at  the  thinnest  portion 
of  this  eccentric  ring,  this  for  the  purpose  of 
providing  approximately  uniform  tension  against 
the  cylinder  walls  at  every  point  on  the  ring 
circle.  A  moment's  thought  will  make  it  evident 
that  since  the  ring  slot  provided  in  the  piston  for 
the  reception  of  the  ring  is  of  uniform  depth, 
while  the  ring  itself  is  of  tapering  form,  there  is 


152  Tractor  Engines. 

going  to  be  a  cavity  or  pocket  between  the  bottom 
of  the  ring  slot  and  the  ring  itself  at  its  narrower 
portions. 

This  fact  taken  into  consideration  with  the 
clearance  left  for  free  movement  of  the  ring  in 
its  slot,  makes  it  possible  for  the  highly  com- 
pressed gases  above  the  piston  to  work  through 
this  clearance,  in  behind  the  ring,  and  then  out 
again  at  the  bottom,  escaping  to  the  crankcase 
chamber. 

The  second  purpose  of  the  lubricant  on  the 
cylinder  walls,  then,  is  quite  obvious.  It  must 
serve  to  set  up  an  oil  seal  adapted  to  fill  this 
clearance  and  prevent  the  gases  from  working 
in  behind  the  piston  ring  and  making  good  their 
escape.  And  by  the  way  it  performs  this  second 
function,  taking  »into  consideration  also  its  effi- 
ciency as  a  lubricant,  so  is  an  oil  judged  proper 
or  improper  for  tractor  engine  use. 

Any  oil,  to  be  of  service  either  as  a  lubricant  or 
to  maintain  this  desired  piston  ring  seal,  must  be 
capable  of  thorough  and  even  distribution  to 
every  point  in  the  engine  where  a  lubricant  is  re- 
quired through  the  system  of  distribution  pro- 
vided by  the  engine  designer.  In  determining 
the  proper  lubricant  for  the  engine,  therefore, 
our  first  consideration  'will  be  an  analysis  of  the 
system  of  lubrication  employed. 

Speaking  generally,  all  tractor  engine  lubricat- 
ing systems  can  be  classified  under  five  separate 
distinct  headings.  Perhaps  the  simplest  is  the 
plain  splash  system  illustrated  in  Figure  102.  In 
this  system  the  fresh  oil  is  contained  in  a  reser- 
voir absolutely  distinct  and  separate  from  the 
crankcase  and  is  fed  to  the  crankcase  in  exactly 
the  proper  amount  to  maintain  a  constant  level 
in  the  crankcase  itself.  The  oil  feed  is  accom- 
plished by  means  of  a  plunger  pump  which  is  ad- 


Lubrication  of  the  Engine.        153 

justable,  as  to  plunger  stroke,  so  that  the  oil  feed 
can  be  adjusted  to  meet  the  operating  conditions. 
Oil  dippers  or  splashers  on  the  lower  ends  of 
the  connecting  rods  dip  into  the  oil  and  splash 
the  lubricant  up  in  the  form  of  a  fine  spray, 
projecting  it  to  the  cylinder  walls  for  the  lubri- 
cation of  the  cylinders,  pistons  and  piston  rings 
and  to  wells  provided  over  the  mainshaf t,  cam- 
shaft and  piston  pin  bearings,  and  in  most  in- 
stances to  a  well  under  the  mainshaft  timing 
gear.  Some  of  the  spray  is  projected  to  the 
cams  themselves,  the  cam  followers,  and  in  some 
cases  to  the  valve  stems  for  their  lubrication. 

Two  methods  are  employed  for  conducting  the 
oil  into  the  crankpin  bearings ;  the  more  usual 

is  to  drill  through  the 
connecting  rod  bear- 
ing cap  just  in  front 
of  the  splasher,  so 
that  the  impact  of  the 
^^  rod  with  the  oil  drives 

F/6.J02  ^F  the  oil  into  the  bear- 

Fig.   102.     Splash  system.  *ng  J      the    .  leSS     USUal 

method  is  to  drill 
and  counterbore  two  small  holes  in  the  connect- 
ing rod  bearing  upper  half  at  each  side  of  the 
rod  proper  by  means  of  which  a  quantity  of  oil 
is  enabled  to  reach  the  crankpin  bearing. 

This  system  is  known  as  the  "all  loss  sys- 
tem," for  the  reason  that  none  of  the  oil,  after 
use,  is  returned  to  the  reservoir ;  all  the  oil 
pumped  into  the  crankcase  is  either  used  or 
thrown  off  by  the/ action  of  the  engine. 

In  order  to  provide  efficient  and  even  distri- 
bution of  the  oil  throughout  the  crankcase 
chamber,  insuring  a  copious  supply  to  every  bear- 
ing and  rubbing  surface,  it  is  essential  that  the 
oil  splashed  by  the  connecting  rod  dip  be 


154  Tractor  Engines. 

thoroughly  atomized  or  broken  up  into  a  form 
where  it  is  readily  carried  or  floated  on  the 
trapped  air  to  the  parts  requiring  lubrication.  An 
oil  of  proper  body  to  lend  itself  readily  to  such 
thorough  atomization,  therefore,  is  a  prime 
requisite  with  any  system  where  the  connecting 
rod  dip  or  splash  is  relied  upon  for  the  oil  dis- 
tribution within  the  engine  itself.  Such  an  oil 
must  be  of  medium  or  light  body.  An  oil  too 
heavy  in  body  will  not  be  so  finely  divided  under 
the  connecting  rod  impact  and  this  condition  is 
particularly  emphasized  under  winter  conditions 
when  any  oil  shows  a  tendency  to  thicken  up  or 

to     increase     in    vis- 
cosity. 

Another  point  in 
connection  with  the 
"all  loss"  system  is 
fact  that  the  oil  in  the 
crankcase  is  constant- 
ly  being  built  up,  as 
sysFtegm. 103'  Splash  circulating  to  body  and  quality, 

by  the  addition  of  the 

fresh  oil  supplied  by  the  pump  or  mechanical 
oiler,  as  the  case  may  be.  Obviously,  therefore, 
an  oil  of  lighter  body  can  be  used  more  effect- 
ively than  is  the  case  where  the  whole  oil  reserve 
is  circulated  and  contaminated  by  the  admixture 
of  fuel  and  carbon  sediment. 

The  second  lubricating  system  is  the  splash 
circulating  system  illustrated  in  Figure  103.  In 
this  system  the  bottom  of  the  crankcase  forms  an 
oil  reservoir  from  which  the  oil  is  pumped,  usu- 
ally by  a  gear  pump  and  less  frequently  by  a 
plunger  pump  or  the  centrifugal  action  of  the 
engine  flywheel,  either  to  dipper  troughs,  located 
one  under  each  connecting  rod,  or  to  open  wells 
over  the  mainshaft  bearings  from  which  the 


ic 
:d 

' 


Lubrication  of  the  Engine.        155 

overflowing  oil  supplies  the  dipper  troughs. 
Suitably  placed  orifices  in  the  dipper  troughs 
serve  to  maintain  -  the  oil  level  constant  so  that 
the  connecting  rod  dip  is  always  the  same. 

It  will  be  seen  that  in  this  instance  it  is  not 
essential  that  the  quantity  of  oil  supplied  by  the 
pump  be  regulated  to  coincide  with  that  used  in 
the  lubrication  of  the  engine.  As  a  matter  of 
fact,  the  flow  is  always  considerably  in  excess  of 
what  the  engine  is  using,  and  this  excess  over- 
flows from  the  dipper  troughs  back  to  the  reser- 
voir for  re-circulation  by  the  pump.  The  cylin- 
der walls,  pistons  and  piston  rings  and  all  the 

various  bearing  sur- 
faces are  lubricated 
by  the  connecting  rod 
splash  exactly  as  with 
the  plain  splash  sys- 
tem. 

Obviously,  in  order 
to  provide  for  thor- 
™gh  atomization  of 
the  oil  and  consequent 
thorough  and  even  distribution,  an  oil  of  light  or 
medium  body  should  be  used.  On  the  other  hand, 
due  to  the  fact  that  the  oil  is  constantly  being  cir- 
culated at^I  subjected  to  wear  and  tear  in  the  en- 
gine itself,  as  a  result  of  its  usage  and  re-usage, 
in  order  to  provide  maximum  lubrication  an  oil 
of  heavier  body  is  required  than  with  the  splash, 
"all  loss"  system.  The  splash  circulating  sys- 
tem by  its  nature  is  best  adapted  for  handling  a 
medium  bodied  oil. 

Third  in  line  comes  the  force  feed  and  splash 
system  illustrated  in  Figure  104.  Here  we  have 
the  oil  contained  in  a  crankcase  reservoir  exactly 
as  with  the  splash  circulating  system,  and  forced 
by  a  gear  or  plunger  pump  to  each  of  the  main- 


156 


Tractor  Engines. 


shaft  bearings  under  pressure,  and  in  some  in- 
stances also  to  the  camshaft  bearings.  .  As  a  rule, 
in  order  to  maintain  the  pressure  approximately 
constant  regardless  of  variations  in  engine  speed, 
a  safety  valve  or  by-pass  is  placed  in  the  oil 
header  and  set  to  permit  any  excess  oil  delivered 
by  the  pump  to  be  projected  onto  the  timing- 
gear  train  for  lubrication  of  these  gears. 

The  oil  bleed  from  the  mainshaft  bearings 
serves  to  maintain  a  constant  level  in  the  dipper 
troughs  which,  as  with  the  splash  circulating  sys- 
tem, are  equipped  with  properly  placed  overflow 
orifices  so  that  too  high  a  level  cannot  be  reached. 
With  .the  exception  of  the  mainshaft  bearings—- 
rarely the  camshaft  bearings — and  the  timing- 
gear  train,  the  dis- 
tribution of  the  lubri- 
cant to  the  various 
surfaces  is  exactly 
the  same  as  with  the 
splash  circulating  sys- 
tem. The  conditions 
encountered  in  this 
system  being  so  near- 
ly identical  with  those  on  the  splash  circulating 
system,  it  is  evident  that  this  system  also  will 
operate  at  its  best  when  a  medium  bodied  lubri- 
cant is  employed. 

In  the  fourth  system  of  lubrication  the  con- 
necting rod  splash  is  done  away  with.  It  is  called 
the  force  feed  system  and  is  illustrated  in 
Figure  105.  As  with  the  force  fee'd  and  splash 
system,  the  oil  is  fed  by  pump  pressure  to  each  of 
the  mainshaft  bearings  and  sometimes  to  the 
camshaft  bearings.  An  oil  by-pass  is  incor- 
porated in  the  system  to  maintain  the  pressure 
approximately  constant.  From  the  mainshaft 
bearings  the  oil  is  conducted  either  through  drill- 


.  105 

Fig.  105.     Force  feed  system. 


Lubrication  of  the  Engine.        157 

ings  in  the  crank-webs  or  through  the  hollow 
crankshaft  to  the  crankpin  bearings  under  pump 
pressure. 

The  oil  bleed  from  the  crankpin  bearings  is 
projected  in  the  form  of  a  very  fine  spray  to  the 
cylinder  walls  for  the  lubrication  of  the  cylin- 
ders, piston  and  piston  rings ;  and  to  the  piston 
pin  bearings,  the  cams,  the  cam  followers  and,  in 
some  cases,  to  the  camshaft  bearings,  where 
these  are  not  taken  care  of  under  pressure.  The 
excess  oil,  draining  back  from  the  crankcase 
chamber  walls,  reaches  the  reservoir  and  is  re- 
circulated  by  the  pump. 

Here  we  have  a  condition  where  the  more  im- 
portant bearings  are 
fed  directly  under 
pressure  from  the 
pump;  it  is  also  ap- 
parent that  since  the 
oil  spray  results  from 
the  oil  being  pro- 
jected through  the 
for  very  small  annular 

passage  on  either  side 

of  the  crankpin  bearing  under  pump  pressure, 
augmented  by  centrifugal  force,  we  have  a  posi- 
tive means  of  finely  dividing  or  atomizing  the  oil 
so  that  the  use  of  a  heavier  lubricant  than  that 
best  adapted  for  splash  distribution,  is  made  pos- 
sible. The  force  feed  system,  where  the  oil  pump 
is  submerged  in  the  reservoir  so  that  there  will  be 
no.  question  as  to  the  pump  drawing  a  full  supply 
when  the  engine  is  started  and  the  oil  is  chilled, 
is  preeminently  adapted  to  handle  medium 
heavy-bodied  and  heavy-bodied  oils. 

There  is  not  a  great  deal  of  difference  between 
the  force  feed  lubrication  system  and  the  full 
force  feed  system  (Figure  106.)  The  pressure 


158 


Tractor  Engines. 


line  is  carried  one  step  further  and  the  oil  is  led 
up  from  the  crankpin  bearings  to  the  piston  pin 
bearings  by  means  of  an  oil  pipe  attached  to  the 
side  of  the  connecting  rod,  so  that  the  piston  pin 
bearing  is  also  fed  under  pressure.  The  oil  bleed 
from  the  crankpin  bearings,  however,  is  relied  on 
for  the  lubrication  of  the  cylinder  walls,  pistons 
and  piston  rings,  cams ;  generally  also  the  cam- 
shaft bearings  and  the  cam  followers.  A  by-pass 
and  oil  pressure  regulator,  as  a  rule,  takes  care 

of  the  timing- 
gear  lubrication. 
Obviously,  the 
full  force  feed 
system  is  like- 
wise adapted  to 
the  distribution 
of  a  heavy- 
bodied  lubricant. 
It  was  pointed 
out  before  that 
there  are  many 
little  points  of 

FK    107.     Splash    circulating   system     diversion  in  lllb- 
as  applied  to  the  All-Work  tractor   en-        *       ,  . 

gine.  jicating  systems 

which     would 

seem,  at  first  sight,  to  make  them  fall  without 
bounds,  so  to  speak,  with  regard  to  these  five 
classifications.  Take,  for  instance,  the  type 
wherein  a  mechanical  oiler  is  used,  the  oil  being 
forced  to  each  of  the  bearings  and  to  the  cylin- 
der walls  under  pressure.  This  can  be  classified 
as  a  force  feed  system  in  which  a  series  of 
pumps — one  for  each  oil  lead,  in  fact — is  sub- 
stituted for  the  single  pump  used  on  the  ortho- 
dox system.  It  is  not  a  circulating  system,  how- 
ever, since  the  oil  is  not  returned  to  the  reservoir. 
Such  a  system  can  be  used  for  the  distribution 


Lubrication  of  the  Engine.        159 


of  either  heavy,  medium-bodied  and  light-bodied 
lubricants,  but  the  necessity  of  using  exposed  oil 
leads  demands  a  lubricant  of  sufficient  fluidity 
for  efficient  distribution  under  winter  temper- 
atures. 

It  must  be  considered  that  the  details  in  the 
arrangement  of  these  systems  will  greatly  affect 
the  choice  of  the  lubricant  as  to  body.  For  in- 
stance, as  was  pointed  out  before,  an  oil  pump 
submerged  in  the  lubricant  is  better  adapted  to 


Fig.    108.      Arrows   show    course   oil   takes   from   oil   reservoir 
through  the  motor  on  All-Work  tractor. 

handle  a  heavier  oil  than  an  elevated  pump;  and 
this  condition  is  greatly  emphasized  under  winter 
temperatures.  Likewise  a  submerged  gear  pump 
is  better  adapted  to  handle  a  congealed  or  thick- 
ened oil  than  a  plunger  pump,  which  depends  on 
suction  for  its  initial  charge.  On  the  other  hand, 
an  elevated  plunger  pump  is  better  adapted  to 
function  properly,  except  at  low  temperatures, 
than  an  elevated  gear  pump,  since  the  latter  can- 


160 


Tractor  Engines. 


Lubrication  of  the  Engine.        161 

not  be  packed  tight  enough  to  insure  its  being 
primed  sufficiently  after  a  stop  of  considerable 
duration,  to  circulate  the  oil  immediately  the 
engine  is  started. 

Where  conditions  tending  toward  irregular 
pump  action  are  encountered  in  the  lubricating 
system,  in  order  to  insure  that  degree  of  positive 
action  which  is  essential  to  correct  motor  per- 
formance and  power  production,  we  naturally 
are  going  to  use  a  lighter  grade  of  oil,  which  is 
easier  to  move,  than  the  general  analysis  of  the 
lubricating  system  as  applied,  would  seem  to 
call  for. 

Having  analyzed  the  system  of  lubrication  and 
determined  from  its  general  type,  and  from  the 
details  of  its  construction,  which  is  the  proper 
grade  of  oil  for  use  with  it,  our  next  step  will  be 
to  analyze  the  engine  construction  with  the  view 
of  determining  whether  the  oil,  as  recommended, 
will  properly  perform  its  functions.  For  in- 
stance, not  all  tractor  engine  designers  are  of  the 
same  opinion  as  to  piston  material  and  piston 
clearance ;  nor  are  all  of  them  sold  on  the  eccen- 
tric piston  ring  as  against  the  concentric  type 
which  eliminates,  to  a  greater  or  less  extent,  the 
oil  cavity  or  pocket  behind  the  ring. 

We  will  find,  therefore,  that  one  engine  when 
cool  will  have  a  greater  piston  clearance  than 
another,  and  while  it  is  the  object  of  every 
tractor  engine  designer  to  bring  this  clearance  as 
close  as  is  consistent  with  free  piston  movement 
and  a  high  factor  of  safety  against  piston  seizure, 
still  even  at  normal  operative  temperatures  we 
are  going  to  find  a  great  divergence  in  the 
amount  of  piston  clearance  between  engines  of 
different  design  and  different  manufacture. 

Nor  are  all  production  methods  identical. 
One  manufacturer  will  produce  his  cylinders  by 


162 


Tractor  Engines. 


a  double-rough-cut-and-ream  finished  method, 
whereas  another  will  produce  a  fine  cylinder 
wall  finish  by  the  grinding  method. 

The  oil,  as  determined,  must  be  of  a  grade 
which  not  only  will  lend  itself  to  perfect  distri- 
bution through  the  oiling  system,  but  will  also 
maintain  the  proper  piston  ring  seal  at  normal 
operative  temperatures  with  mechanical  clear- 
ances as  encountered  in  the  particular  engine 
under  consideration. 


FIG.  IIO 


Fig.  110.  The  Big  Bull  force  feed  circulating  oiling  system 
forces  the  oil  through  a  hollow  crank  shaft  and  delivers  it  to  the 
inside  of  the  connecting  rod  bearings.  Reduces  the  amount  of 
oil  used  and  is  a  positive  feed,  so  long  as  there  is  oil  in  the 
reservoir.  The  operator  can  see  the  oil  flow  all  the  time  from 
his  seat. 

Considering  the  bad  effects  of  non-main- 
tenance of  this  piston  ring  seal,  let  us  assume 
that  we  have  the  engine  with  one  of  the  pistons 
up  nearly  at  the  top  of  its  compression  stroke. 
Above  the  piston  we  have,  then,  a  more  or  less 
wet  mixture  of  gasoline  and  kerosene  vapor  and 
air  compressed  to>  approximately  60  pounds  per 


Lubrication  of  the  Engine.        163 

square  inch,  depending  on  the  compression  ratio 
of  the  engine  and  the  position  of  the  crankpin. 
Since  the  piston  ring  seal  is  not  being  properly 
maintained,  some  of  this  wet  mixture  will  work 
down  past  the  pistons,  "blow  by"  the  rings  and 
the  gasoline  or  kerosene,  either  of  which  is  a 
first-class  solvent  of  the  mineral  lubricating  oil, 
will  wash  the  lubricant  from  the  cylinder  walls, 
further  aggravating  the  situation,  and  paving  the 
way  for  increased  "blow-by"  on  the  next  com- 
pression stroke. 


Fig.   111.      Splash  circulating  system  as  modified  by  Avery. 

In  the  meantime  we  have  lost  to  the  crankcase 
chamber  from  the  combustion  chamber  a  quan- 
tity of  fuel — a  certain  portion  of  the  heat  units 
which  we  were  counting  on  to  develop  full 
p>ower  from  the  engine.  More  than  that,  we  have 
reduced  the  compression,  due  to  this  loss,  and 
since  the  power  that  the  internal  combustion  en- 
gine is  capable  of  developing  is  dependent  almost 
directly  upon  the  compression  pressure,  within 
limits,  we  have  in  this  another  source  of  reduced 
power  output  or  loss  in  efficiency.  Still  a  third 


164  Tractor  Engines. 

source  is  the  lack  of  effective  lubricant  on  the 
cylinder  walls,  which  increases  the  piston  fric- 
tion, causing  a  power  loss  and  a  tendency  to 
overheat,  as  well  as  a  tendency  for  rapid  wear  of 
the  pistons,  piston  rings  and  the  cylinder  walls. 

Let  us  neglect  for  a  moment  the  amount  of 
mixture  which  has  escaped  down  into  the  crank- 
case  chamber,  and  let  us  consider  that  we  have 
turned  the  engine  over  past  its  top  dead  center 
and  that  it  is  now  on  its  power  stroke.  We  now 
have  above  the  piston  a  quantity  of  intensely  hot 
gases  at  very  high  pressure.  The  temperature 

range  will  be  between 
2000°  to  3000°  F., 
while  the  pressure 
will  be,  roughly,  four 
times  the  compression 
pressure,  or  some- 
wheres  in  the  neigh- 
borhood  of  250 
pounds  per  square 

Fig.   112.     Force-feed  lubricator.        inch.  These       gaSCS 

are   made  up   largely 

of  that  inert  constituent  of  the  atmosphere — 
nitrogen — and  of  the  products  of  combustion  of 
the  hydro-carbon  fuel,  which  are  carbon-dioxide, 
carbon-monoxide  and  water  vapor.  There  will 
be  traces  of  other  gases,  which  we  need 'not  take 
into  consideration. 

The  escape  of  these  gases  past  the  piston  has 
two  effects.  One  is,  of  course,  -to  cause  a  reduc- 
tion in  working  pressure  on  top  of  the  piston — * 
our  real  source  of  power — and  consequently  we 
have  still  another  cause  of  power  loss  as  a  result 
of  the  breaking  down  of  the  piston  ring  seal. 
The  second  effect  will  be  greatly  to  augment  the 
temperature  of  the  piston  and  cylinder  walls,  due 
to  the  passage  of  these  intensely  hot  gases 


Lubrication  of  the  Engine.        165 


through  the  clearance  space.  Here  again  we 
have  a  condition  which  tends  to  increase  friction 
and  reduce -power  output. 

Let  us  now  look  into  the  crankcase  chamber 
and  see  what  has  happened  there.  On  the  com- 
pression stroke  we  brought  down  a  quantity  of 
vaporized  fuel,  which  quickly  condensed  in  the 
crankcase  chamber  and  mixed  with  the  oil,  reduc- 
ing its  body  and  impairing,  to  a  greater  or  less  ex- 
tent, its  lubricating  efficiency.  In  aggravated  cases, 
the  body  of  the  oil  will  fall  off  sufficiently  to  im- 
pair seriously 


/7<7.  If 3 


Fig.  113.  Crank  shaft,  showing  how 
the  oil  is  carried  to  the  bearings  on 
Leader  tractor  engine. 


the  lubrica- 
tion of  the 
engine  bear- 
ings and  we 
wilf  have  in- 
creased fric- 
tion between 
all  the  mov- 
ing surfaces 
and  a  tend- 
ency for  the 
bearing  sto  roughen  up  in  service. 

On  the  power  stroke  the  escaping  gases  car- 
ried down  with  them  a  quantity  of  water  vapor 
which  has  also  condensed  in  the  cooler  crankcase 
chamber;  and  being  heavier  than  the  oil  it  has 
been  deposited  at  the  bottom  of  the  oil  reservoir 
or  else,  due  to  favorable  oil  temperature  condi- 
tions, has  formed  an  emulsion  with  the  oil.  In 
the  former  case  the  water  will  naturally  settle 
in  the  oil  pump — usually  the  lowermost  point  in 
the  reservoir — and  in  case  of  a  cold  snap  will 
freeze  up,  locking  the  pump,  resulting  in  a  condi- 
tion which  will  cause  breakage  of  the  oil  pump- 
shaft  if  the  engine  is  started  without  first  being 
warmed  up.  In  the  second  case,  the  mixture  of 


166  Tractor  Engines. 


oil  and  water  is  not  conducive  to  proper 
lurication. 

There  is  still  another  effect  which  we  have  not 
considered.  Let  us  now  turn  the  engine  over 
until  the  piston  is  on  the  intake  stroke.  We  then 
have  reduced  pressure  in  the  combustion  cham- 
ber above  the  piston  and  atmospheric  pressure 
in  the  crankcase  chamber,  and  since  the  oil  is  not 
of  the  character  needed  to  maintain  proper  pis- 
ton ring  seal,  we  are  going  to  get  a  "blow-by"  in 
the  other  direction,  and  this  upward  "blow-by"  is 
going  to,  carry  a  quantity  of  the  lubricant  up  into 
the  combustion  chamber  where,  being  slow 
burning,  it  is  going  to  tend  to  produce  carbon 
deposit.  This  is  a  condition  which  must  not  be 
lost  sight  of. 

It  will  be  seen,  therefore,  that  the  condition  as 
to  piston  clearance,  and  the  ability  of  the  lubri- 
cant to  maintain  an  effective  piston  ring  seal,  is 
going  to  be  second  in  importance  in  the  deter- 
mination of  the  proper  grade  of  lubricant  only 
to  the  system  of  lubrication  itself.  Other  fac- 
tors which  must  be  taken  into  serious  considera- 
tion are  the  normal  operative  temperatures  of 
the  engine;  the  cylinder  arrangement,  the  valve 
arrangement;  the  engine  speed;  climatic  con- 
ditions, etc. 

It  is  a  fact,  however,  that  each  of  these  fac- 
tors is  so  interlinked  and  influenced  by  some  or 
all  of  the  others,  that  it  takes  an  experienced 
automotive  engineer,  who  is  not  only  thoroughly 
grounded"  as  to  tractor  engine  design  and  prac- 
tice, but  who  also  has  had  broad  practical  expe- 
rience with  tractor  operation  in  the  field,  to  size 
up  the  situation  as  regards  any  particular  engine 
and  make  an  oil  determination  on  a  scientific 
basis.  And  at  that,  such  a  man  must  also  be 
thoroughly  equipped  with  a  knowledge  of  the 


Lubrication  of  the  Engine.        167 

characteristics  as  well  as  the  character  of  the 
various  grades  of  lubricating  oils  he  has  under 
consideration. 

For  the  average  tractor  owner  or  operator  to 
try  and  judge  the  quality  and  lubricating  value 
of  one  oil  as  against  another  by  so-called  oil 
tests,  which  are,  at  best,  mere  guess-work  as  he 
applies  them,  is  foolhardy.  With  lubricants,  as 
with  other  commodities,  quality  counts,  and 
quality  cannot  be  obtained  without  careful  atten- 
tion to  detail  in  process  and  procedure  at  the  oil 
refinery;  and  this  very  carefulness,  which  is  the 
tractor  owner's  safeguard  as  to  lubricating  value, 
means,  of  course,  increased  cost.  It  could  not 
be  otherwise. 

Every  reputable  oil  manufacturer  maintains  a 
corps  of  highly  trained  technicians,  who  make  a 
sufficient  number  of  both  physical  and  chemical 
tests  in  a  fully  equipped  laboratory  and  under 
conditions  which  assure  the  utmost  in  accuracy 
to  determine  uniformity  of  product  and  to  elim- 
inate even  slight  variations  in  the  character  of 
their  products  from  day  to  day. 

These  tests,  however,  are  by  no  means  a 
measure  of  the  lubricating  value  of  an  oil.  The 
value  of  an  oil  as  a  lubricant  depends,  first,  upon 
the  stocks  from  which  it  is  made  and  the  pro- 
cess or  processes  employed  in  the  refining  of 
these  stocks;  and  second,  upon  the  process  or 
processes  employed  in  combining  these  stocks. 
Upon  these  two  features  alone  depends  the 
character  of  the  lubricant  and  no  tests  which  it  is 
within  the  power  of  the  average  oil  user  to  make 
can  determine  them. 

The  safest  and  best  course  for  the  tractor 
operator  is  to  buy  the  best  oil  the  market  offers, 
quite  regardless  of  the  cost,  and  to  use  the  par- 
ticular grade  of  that  oil  for  his  tractor  engine 


168  Tractor  Engines. 

which  the  oil  manufacturer  has  specified  for  this 
purpose.  If  this  plan  is  followed,  the  tractor 
owner  will  find  that  the  recommendation  offered 
him  by  the  oil  manufacturer  has  been  determined 
only  after  careful  analysis  of  his  engine  con- 
struction by  a  lubricating  engineering  staff,  every 
member  of  which  not  only  knows  tractor  engines 
from  front  to  rear  and  also  "crosswise,"  but  also 
is  thoroughly  versed  in  what  the  lubricants,  as 
recommended,  will  and  will  not  do  and  the 
reasons  therefor. 

DETAILED  CARE  OF  LUBRICATING  SYSTEMS. 

There  is  not  a  great  deal  that  need  be  said' 
with  regard  to  the  care  of  the  lubricating  sys- 
tems which  fall  under  the  circulating  classifica- 
tion. The  principal  point  to  bear  in  mind  is  to 
keep  the  reservoir  well  filled,  as  indicated  by  the 
level  gauge,  so  as  to  be  sure  that  the  engine  has 
plenty  of  oil. 

For  the  benefit  of  readers  in  doubt  as  to  which 
grade  of  oil  to  use,  a  chart  is  appended  covering 
most  tractors  on  the  market  at  present;  This 
chart  has  been  carefully  prepared  by  experienced 
lubrication  engineers  and  the  user  will  do  well 
in  following  it  to  the  letter.  But  in  doing  so,  see 
to  it  that  you  obtain  the  best  lubricant  that  the 
market  affords ;  it  ,4s  well  worth  the  additional 
cost. 

With  circulating  systems,  frequent  draining  of 
the  system  and  refilling  with  fresh  oil  is  essen- 
tial for  the  reason  that  there  always  will  be  a 
certain  amount  of  fuel  admixture  which  will  im- 
pair the  quality  of  the  oil  and  its  value  as  a  lub- 
ricant; also  a  certain  amount  of  sedimentation, 
particles  of  metal,  carbon  and  grit  drawn  in 
through  the  breather  pipe. 


Lubrication  of  the  Engine.        169 

Where  kerosene  is  used  as  fuel,  the  best  plan 
is  to  drain  the  reservoir  after  every  25  hours  of 
service,  draining  while  the  engine  is  still  warm, 
so  as  to  carry  out  the  last  trace  of  sediment. 

Where  the  fuel  is  gasoline,  once  in  50  hours 
is  generally  sufficient  for  draining. 

Do  not  flush  out  the  crankcase  with  kerosene 
after  draining,  as  some  of  the  kerosene  will  be 
trapped  in  the  dipper  troughs  or  other  basins  in 


12  Drtfc*  pof  MM 


Fig.  114.  Adjustment  of  mechanical  oiler  on  the  Aultman- 
Taylor  tractor. 

the  engine  and  will  remain  to  impair  the  quality 
of  any  fresh  oil  added.  The  best  plan  is  to  drain, 
wash  out  with  a  quart  of  fresh  oil,  and  then 
refill  the  system  with  new  oil. 

When  the  oil  pan  can  be  removed  from  the 
bottom  of  the  engine  so  that  all  points  can  be 
reached  and  mopped  out,  the  system  can  safely 
be  washed  out  with  kerosene — not  otherwise, 
however. 


170 


Tractor  Engines. 


The  care  and  adjustment  of  systems  employ- 
ing the  force  feed  mechanical  lubricator  can  be 
gathered  from  the  following  excerpts  from 
manufacturers  instruction  books  dealing  with  the 
subject : 

DIRECTIONS  FOR  DETROIT  FORCE-FEED  OILER. 
(Figure  115.) 

Be  sure  the  tank,  or  reservoir,  is  perfectly 
clean  before  filling  with  oil  the  first  time.  ? Any 

foreign  substance 
is  apt  to  injure 
your  engine's 
bearings. 

Be  sure  to 
strain  your  oil  be- 
fore filling  the 
tank — always. 

To  fill,  unscrew 
the  filler  cap  "A" 
and  pour  in  the 
oil. 

Amount  of  oil 
in  tank  is  shown 


/V<3 


i WJ 


Fig.    115. 
oiler. 


A<  by  the  position  of 

the  pointer.  If 

it  points  to  "EMP"  the  tank  is  empty;  if  it 
points  to  "FULL"  the  tank  is  full.  Different 
levels  are  indicated  by  the  different  positions  of 
the  pointer. 

Regulation  of  each  feed  is  accomplished  by 
adjusting  the  button  "C"  in  front  of  that  feed. 

When  the  small  stop  or  projection  with  the 
zero  mark  (0)  on  the  bottom  of  "C"  is  against 
and  on  the  right-hand  side  of  the  stop/ pin  so 
that  the  zero  mark  is  in  line  with  the  mark  "D" 
no  oil  is  being  fed. 

To  feed,  turn  the  button  to  the  left,  or  in  a 


Lubrication  of  the  Engine.        171 

counter  clockwise  direction.  One  complete  turn 
to  the  left  opens  the  feed  to  full  capacity. 

To  decrease  the  feed,  turn  to  the  right,  or  in 
a  clockwise  direction. 

The  regulating  buttons  are  slotted  for  a  screw- 
driver, coin  or  other  flat  piece  of  metal,  as  the 
adjustment  is  purposely  made  stiff. 

Once  the  feeds  are  adjusted,  no  further  regu- 
lation is  necessary. 

It  is  not  necessary  to  turn  off  the  feeds  every 
time  the  engine  stops.  The  force  feed  oiler 
starts  and  stops  automatically  with  the  engine. 

To  adjust  the  feed  of  oiler  to  your  engine: 
Every  engine  is  different  from  •  every  other  en- 
gine and  no  absolute  rules  can  be  laid  down  as 
to  the  exact  quantity  of  oil  required  for  your 
engine. 

If  your  engine  is  new,  pour  about  a  quarter  of 
a  teacup  of  oil  through  the  spark  plug  hole  on 
each  cylinder  and  turn  the  engine  over  by  hand 
several  times  to  be  sure  the  cylinder  and  ringf 
are  thoroughly  lubricated  before  starting.  Pour 
oil  in  each  crankcase,  too. 

The  best  way  to  do  this  is  to  feed  plenty  of 
oil  at  first.  Take  one  feed  at  a  time  and  very 
slowly  and  gradually  cut  down  the  amount  of 
oil  fed  to  the  one  bearing  until  you  have  found 
the  least  amount  of  oil  that  will  give  adequate 
and  perfect  lubrication.  After  one  feed  is  ad- 
justed, the  others  can  be  regulated  in  the  same 
way. 

Great  eare  will  have  to  be  taken  in  this  pro- 
cess not  to  feed  so  little  oil  that  a  bearing  is 
burned  out  or  a  crankshaft,  piston  or  cylinder 
scored.  Overheating  and  squeaking  are  signs  of 
too  little  lubricating  oil  being  fed. 

Blue  smoke  at  the  exhaust  indicates  too  much 


172 


Tractor  Engines. 


lubricating  oil  to  the  cylinder.     Black  smoke  in- 
dicates too  much  gasoline. 

ADJUSTING  OILER  ON  BULL  TRACTOR. 
(Figure  116.) 


Do  not  close  off  feed  valves  on  lubricator 
until  the  motor  has  run  several  days,  and  then 
with  caution. 

All  inside  parts  of  motor  are  lubricated  with  a 
six-way  force-feed  oiler. 


Fig.    116.     Adjusting   mechanical   oiler. 

Before  starting  motor,  be  sure  this  oiler  is 
filled  with  good  clean  oil,  and  turn  oiler  by  hand 
to  see  that  it  pumps  freely. 

Always  keep  oil  in  the  crankcase  up  to  level 
with  drain  cock  on  the  flywheel  side  of  crank- 
case,  but  never  above  the  level. 

After  motor  starts  be  sure  that  every  pipe  is 
feeding  properly.  You  will  find  pipes  running 
to  cylinders,  main  bearings  and  connecting  rod 
bearings. 

After  the  engine  has  been  run  several  days 


Lubrication  of  the  Engine.        173 

and  the  journals  are  well  seated,  adjust  the  feed 
pipes,  as  follows : 

Front  cylinder,  four  to  five  drops ;  rear  cylin- 
der, leave  wide  open.  Main  bearings,  four  to 
five  drops,  leave  connecting  rod  bearing  feeds 
wide  open. 

Each  feed  pipe  has  a  separate  adjustment.  If 
lead  pipes  overflow,  the  motor  should  be  stopped 
and  the  pipes  cleaned  out  at  once. 

WHAT   OIL  TO   USE   IN   YOUR   TRACTOR. 


SUMMER 


WINTER 


Acme 

Albert    Lea  

Medium  heavy 

Medium 

Allis-Chalmers    . 

Medium 

Allis-Chalmers  (General  Purpose)... 
All  Work  

Medium 
Heavy 

Medium 
Medium 

Appleton    

Medium  heavy 

Medium 

Atlas 

Medium 

Aultman-Taylor    

Heavy 

Medium 

Aultman-Taylor  (22-45) 

Medium  hea^y 

Medium 

Aultman-Taylor  (15-30)  (Waukesha) 
Automotive   

Medium  heavy 
Medium  heavy 

Medium 
Medium 

Auto-Tiller 

Light  medium; 

Avery  (5-10  H  P  ) 

Medium 

Medium 

Bates    Steel   Mule  

Heavy 

Medium 

Bean   Track-Pull  

Medium 

Medium 

Beaver   (Brantford    Canada) 

Medium 

Beeman  Garden  Tractor  

Medium 

Medium        s 

Belt  Rail.  . 

Medium  heavy 

Medium 

Best  

Heavy 

Medium 

Big  Bull 

Heavy 

Medium 

Blue    "J"  

Medium  heavy 

Medium 

Buckeye   (Ohio) 

Heavy 

Medium 

Cleveland  

Medium  heavy 

Medium 

Coleman    ... 

Heavy 

Medium 

Medium  heavy 

Medium 

COD 

Medium 

Craig     ...                      

Medium  heavy 

Medium 

Creeping     Grip  

Medium  heavy 

Medium 

Cultitractor     

Medium  heavy 

Medium 

Dakota 

Medium  heavy 

Medium 

Depue  

Medium  heavy 

Medium 

Eagle    . 

Medium  heavy 

Medium 

Heavy 

Medium 

Fageol  

Medium  heavy 

Medium 

Farm  Horse 

Heavy 

Medium 

Fitch  Four  Drive  

Medium  heavy 

Medium 

Flour  City  

Heavy 

Medium 

Medium 

Medium 

Frick   . 

Heavv 

Medium. 

174 


Tractor  Engines. 


SUMMER 

WINTER 

Galloway    .                             ..*... 

Heavy 

Medium 

Gehl    

Medium  heavy 

Medium 

Gile 

Gilson    (12-25)                         

Heavy 

Medium 

Gilson    (15-30) 

Medium  heavy 

Graham  

Medium  heavy 

Medium 

Grain   Belt 

Medium  heavy 

Medium 

Gray   

Medium  heavy 

Medium 

Hart  Parr  

Heavy 

Medium 

Heider 

Medium  heavy 

Hession    

Heavy 

Medium 

Hicks 

Heavy 

Hollis    

Medium  heavy 

Medium 

Holt   Caterpillar  . 

Heavy 

Medium 

Holt  Caterpillar   (Model  45)  

Medium  heavy 

Medium 

Huber     

Medium  heavy 

Medium 

Ideal  (Brantford,  Canada)  
Illinois    

Medium  heavy 
Heavy 

Medium 
Medium 

Indiana 

Medium 

International  8-16  
International  15-30  

Medium 
Medium  heavy 

Medium 

Junior  Ideal  (Brantford,  Can.)  
K.  C    Prairie  Dog  

Medium  heavy 
Medium  heavy 

Medium 
Medium 

Medium  heavy 

La  Crosse  

Heavy 

Medium 

Lang 

Heavy 

Medium  heavy 

Leader    

Medium  heavy 

Liberty 

Heavy 

Lightf  oot   

Medium  heavy 

Medium 

Little  Giant 

Medium  heavy 

Maxim    

Heavy 

Medium 

Minneapolis  ... 

Heavy 

Mogul   (I    H    Co  ) 

Medium  heavy 

National  

Medium  heavy 

Medium 

Neverslip    (20-12) 

Heavy 

Neverslip    (30-18,  10-6)    

Medium  heavy 

Medium 

New  Age  .  .    . 

Medium  heavy 

Medium 

Nilson   

Medium  heavy 

Medium 

Oil  Pull  (20-40)  (Rumely  Co.)  
Oil  Pull  (12-20,  16-30)  (Rumely  Co.) 
Oil  Pull  (Rumely  Co.)  

Medium  heavy 
Medium  heavy 
Heavy 

Medium 
Medium 
Medium 

Parrett 

Medium  heavy 

Pioneer  

Heavy 

Medium 

Plow  Man 

Medium  heavy 

Medium 

Porter   

Medium  heavy 

Medium 

Port  Huron  ...                           

Heavy 

Medium 

Reed 

Medium  heavy 

Medium 

Royer  

Heavy 

Medium 

Russell 

Medium  heavy 

Medium 

Russell   (Giant)  

Heavy 

Medium 

Sandusky     .  .            ....        .    . 

Medium  heavy 

Medium 

Heavy 

Medium 

Square  Turn  18-35  

Heavy 

Medium 

Standard 

Medium  heavy 

Medium 

Stinson   

Medium  heavy 

Medium 

Stone    .  .      .  .        .          

Medium  heavy 

Medium 

Strite 

Heavy 

Medium 

Titan  (I.  H.  Co.)  

Medium  heavy 

Medium 

Topp-Stewart                 .  .          .    .  .    .  .  . 

Medium  heavy 

Medium 

Townsend    

Heavy 

Medium 

Lubrication  of  the  Engine.        175 


SUMMER 


WINTER 


Medium  heavy 

Trundaar 

Twin  City  

Heavy 

Medium 

Twin  City  (Model  16) 

Medium  heavy 

Twin  City   (Model  12-20)  
Uncle  Sam  

Medium  heavy 
Medium  heavy 

Medium 
Medium 

Velie 

Victory    

Medium  heavy 

Medium 

Wallis  Cub   (Junior)  
Ward    

Medium  heavy 
Medium  heavy 

Medium 
Medium 

Waterloo  Boy  

Medium 

Medium 

Whitney    

Medium  heavy 

Medium 

Wichita 

Medium  heavy 

Medium 

Wisconsin    

Heavy 

Medium 

Yankee 

Heavy 

Medium 

Yuba  

Medium  heavy 

Medium 

Yuba   (Model  12)                             .    . 

Medium 

Medium 

CHAPTER  VII. 

Cooling. 

Why    It    Is    Necessary    and    Various    Ways 
Which  It  Is  Carried  Out. 

IT  is  necessary  to  waste  some  of  the  heat  gen- 
erated by  the  combustion  of  the  gases  in  the 
engine  cylinders  in  order  to  bring  the  working 
temperature  of  these  cylinders  down  to  a  point 
where  we  can  maintain  a  film  of  oil  between  the 
piston  and  cylinder  walls  and  also  in  order  to 
prevent  the  temperature  from  mounting  so  high 
as  to  cause  warping  and  weakening  of  the  metal 
or  even  melting. 

There  is  another  reason,  and  a  highly  impor- 
tant one,  for  cooling  the  cylinders.  Let  us  con- 
sider that  the  piston  is  on  the  intake  stroke  and 
that  the  various  parts  of  the  engine  are  intensely 
hot.  Immediately  the  cool  incoming  gas  strikes 
the  hot  walls  it  is  heated  and,  naturally,  rapid 
expansion  takes  place  in  accordance  with  the 
degree  to  which  the  gas  is  heated.  This  expan- 
sion, of  course,  tends  to  fill  up  the  space  and  to 
prevent  more  gas  from  entering  the  cylinder  so 
that  we  do  not  get  a,  full  cylinder  charge,  and 
naturally  the  power  of  the  engine  falls  off.  The 
engineer  describes  this  condition  by  saying  that 
the  "volumetric  efficiency"  of  the  engine  is  im- 
paired. 

If,  however,  we  keep  tKe  engine  cylinder  stone 
cold,  which  would  permit  us  to  crowd  in  the 
largest  fuel  charge,  we  have  an  equally  bad  effect 
and  we  lose  power  from  three  causes :'  First, 

(176) 


Cooling.  177 

that  to  keep  the  cylinder  cold  we  must  take  away 
a  very  large  portion  of  the  heat  generated  by  the 
combustion  of  the  gases,  and  every  unit  of  heat 
taken  means  a  loss  of  power ;  second,,  the  chilled 
cylinder  does  not  further  the  complete  vaporiza- 
tion of  the  fuel,  and  it  was  pointed  out  before 
that  vaporization  is  necessary  for  any  body  to 
take  fire  and  burn;  thirdly,  all  those  parts  that 
are  not  vaporized  before  the  fuel  is  ignited  must 
be  vaporized  by  the  heat  liberated  when  the 
vaporized  parts  take  fire,  which  means  that  the 
rate  of  combustion  will  be  slow  and  the  power 
developed  will  be  impaired  as  a  result. 

Besides,  it  being  necessary  for  a  substance  to 
be  vaporized  for  combustion  to  take  place,  it  is 
also  necessary  to  raise  it  to  its  critical  temper- 
ature— that  is,  the  point  at  which  it  will  take  fire 
whether  a  flame  is  present  or  not.  A  match 
applied  to  a  sheet  of  newspaper,  first  converts  a 
small  portion  of  the  paper  into  a  gas  and  raises 
the  temperature  of  this  gas  above  its  critical 
temperature.  The  combustion  of  this  gas  gives 
heat  enough  to  gasify  the  adjacent  paper  and 
heat  up  the  new  gas,  and  so  the  flame  travels 
slowly  along  until  the  whole  paper  is  consumed. 
If,  however,  we  were  to  place  the  sheet  of  paper 
in  a  very  hot  oven,  where  there  was  plenty  of  air 
and  elevate  the  temperature  to  a  point  sufficient 
to  gasify  the  paper  and  ignite  its  gas  the  whole 
sheet  would  burst  into  flame  simultaneously — we 
would  have  very  rapid  combustion. 

In  the  cylinder  of  the  gas  engine  we  simply 
substitute  the  gasoline  mixture  for  the  news- 
paper. When  the  cylinder  is  cold,  the  igniting 
spark  must  raise  a  small  quantity  of  the  mixture 
to  a  point  beyond  the  critical  temperature,  so  that 
it  ignites  and  the  flame  so  started  travels  through 
the  mixture.  But  its  spread  or  travel  is  com- 


178  Tractor  Engines. 


paratively  slow  and  the  power  developed  is  les- 
sened as  a  result. 

If  now,  we  heat  the  gases  up  to  a  point  more 
nearly  approaching  their  critical  temperature,  we 
not  only  insure  thorough  vaporization,  but  we 
also  make  it  easier  for  the  flame  to  travel  once 
it  is  started  by  the  electric  spark,  and  we  get 
very  rapid  combustion  and  greater  power  from 
the  same  amount  of  fuel. 


,  Fig.  117.  Thermo-syphon  cooling  system — solid  arrows  show 
water  circulation;  broken  arrows,  exhaust  and  air  circulation. 
No  water  pump  or  fan  is  used  on  the  Avery  tractor. 

Here,  then,  we  have  two  contradictory  condi- 
tions, one  calling  for  cooling  of  the  cylinder  in 
order  to  give  a  power  increase,  and  the  other 
calling  for  heating  of  the  cylinder  in  order  to 
effect  the  same  result.  In  order  to  strike  the 
best  possible  balance  and  obtain  best  results,  it 
is  apparent  that  a  compromise  is  necessary.  In- 
deed, the  present  internal  combustion  engine  is  a 
compromise  in  many  respects  besides  this. 

All  considered,  best  results   from  the   engine 


Cooling.  179 

are  obtained  when  the  cylinder  walls  are  main- 
tained at  a  temperature  in  the  neighborhood  of 
200  to  225  degrees  F.  In  other  words,  where 
water  cooling  is  adhered  to,  as  in  the  case  of 
practically  all  tractor  engines,  the  temperature  of 
the  cooling  water  emerging  from  the  cylinder 
jackets  should  be  in  the  neighborhood  of  200 
degrees  F.  to  obtain  best  results  from  the  engine. 
The  cooling  system  of  a  typical  engine  is  de- 
tailed in  Figure  117.  The  cylinders  are  sur- 
rounded with  a  jacket  which  is  cast  integral  with 
the  cylinder  block,  and  passages  at  the  top  of 
the  cylinder  block  casting  lead  to  the  head  cast- 
ing to  conduct  the  water  to  a 
similar  jacket  provided  in  the 
latter  (Figure  118-A). 

Water,  like  other  substances, 
expands  when  heated,  except 
between  the  very  narrow  lim- 
its explained  in  the  first  chap- 
ter, which  obviously  does  not 
enter  into  our  present  consid- 
eration. If  we  had  a  cubic 

.Fig.  118-A.     Section        |nch     °f    Water    and    ^^    *> 

showing  cylinder  it  would  occupy  a  space  larger 
than  one  cubic  inch  at  the 
higher  temperature;  but  its  weight  would 
would  be  the  same,  so  that  its  weight  for  a  unit 
of  volume  in  the  second  case  must  be  less  than  in 
the. first.  In  other  words,  the  density  or  specific 
gravity  of  water  decreases  when  the  water  is 
heated,  and  since  an  object  of  less  density  than 
water  will  float  on  water,  it  stands  to  reason  that 
there  will  be  a  tendency  for  heated  water  to  rise 
in  and  float  on  the  top  of  a  body  .of  water  at 
lower  temperature. 

If,  then,  we  have  the  cylinder  jacket  of  the 
engine  filled  with  water  and  the  water  adjacent 


180  Tractor  Engines. 


the  cylinder  walls  becomes  heated,  the  tendency 
will  be  for  this  warmer  water  to  work  to  the  top 
of  the  jacket.  An  outlet  pipe  is  arranged  at  the 
topmost  front  portion  of  the  cylinder  head  casting 
and  this  outlet  is  attached  by  means  of  a  section 
of  rubber  hose  to  a  tank  formed  on  top  of  the 
radiator.  The  radiator  is  composed  of  an  upper 
and  a  lower  tank  connected  together  by  a  series 
of  vertical  copper  tubes  arranged  in  rows  from 
front  to  rear  of  the  radiator ;  the  tubes  are  passed 
through  a  large  number  of  copper  plates  arranged 
one  on  top  of  another  and  spaced  a  short  distance 
apart.  The  purpose  of  these  plates  is  not  so  much 
to  support  the  tubes  as  it  is  to  increase  the  radiat- 
ing surface  providing  a  greaft  area  for  contact  with 
the  air,  just  as  with  a  house- wafming  radiator, 
the  radiating  surface  is  increased  by  increasing 
the  number  of  coils  of  pipe  or  by  providing  cast- 
ings with  large  surface.  It  is  evident,  then,  that 
as  the  water  discharged  from  the  engine  into 
the  top  header  passes  downward  through  these 
tubes,  it  will  be  cooled,  giving  up  some  of  its 
heat  to  the  tubes  from  which  it  is  transferred 
to  the  flanges  and  the  air,  and  in  order  to  insure 
this  transfer  of  heat,  a  fan  is  generally  mounted 
behind  the  radiator  and  belted  to  a  pulley  wheel 
attached  to  the  front  end  of  the  crankshaft  or 
to  some  other  convenient  shaft.  This  fan  creates 
a  suction  which  draws  the  air  through  the  pas- 
sages of  the  radiator  "between  the  flanges  and 
the  vertical  tubes.  In  the  case  of  the  Avery 
tractor,  pictured  herewith,  the  draught  is  created 
by  the  engine  exhaust,  no  fan  being  used. 

From  the  lower  header  of  the  radiator,  another 
pipe  is  arranged  which  conducts  the  water  to  a 
point  on  the  right  side  of  the  engine  near  the 
middle,  where  the  water  enters  at  the  lowest 
point  in  the  engine  water  jacket,  becomes  heated 
again,  rises  and  .continues  the  circulation. 


Cooling.  181 

We  call  such  a  system  which  circulates  the 
water  by  virtue  of  the  natural  tendency  for  the 
water  to  rise  when  heated  and  sink  when  cooled, 
the  natural  circulation  system  or  "thermo-syphon 
system."  It  has  a  couple  of  points  of  advantage 
over  the  system  in  which  the  water  is  circulated 
by  an  engine  pump ;  the  biggest  point  in  its  favor 
is  the  fact  that  it  eliminates  the  pump  and  the 
complication  which  attends  its  installation  and 
use.  Another  point  in  its  favor  is  that  the  water 
does  not  begin  to  move  until  it  becomes  heated, 
so  that  the  cylinders  reach  their  working  temper- 
ature more  quickly  when  the  engine  is  started 
from  cold.  Larger  inlet  and  outlet  water  piping 
is  required  than  with  the  pump  system,  due  to 
the  fact  that  the  force  causing  circulation  is 
limited. 

It  will  be  noticed  that  the  connections  between 
the  engine  and  the  radiator  are  made  .with  rub- 
ber hose  of  the  proper  size  clamped  in  place  with 
suitable  hose  clamps  to  insure  against  the  hose 
slipping  off  and  against  leakage  at  the  joints. 
The  use  of  the  rubber  hose  is  not  so  much  for 
the  purpose  of  simplifying  attachment  and  de- 
tachment  as  it  is  to  protect  the  radiator  from  the 
vibration  when  the  engine  is  in  operation  which, 
were  metal  pipe  used,  would  be  transmitted 'to 
the  radiator  and  soon  cause  rupture  of  the  joints. 

It  is  necessary  to  keep  the  radiator  full  of 
water  at  all  times.  Filling  is  accomplished  by 
taking  off  the  radiator  cap 'and  pouring  in  clean 
water,  preferably  rain  water  or  soft  water;  use 
hard  well  water  only  when  none  other  can  be 
obtained  and  replace  with  soft  water  at  first 
opportunity.  Screw  the  radiator  cap  back  firmly 
in  place  when  the  radiator  is  filled,  to  guard 
against  its  working  off.  There  is  a  small  over- 


% 

182  Tractor  Engines. 

flow  pipe  or  tube  leading  from  inside  the  filler 
neck  on  the  radiator  down  the  rear  right  side  of 
the  device  to  a  point  beneath  the  pan.  'This  is 
to  provide  for  expansion  of  the  water  which  al- 
ways takes  place  when  the  water  is  heated  and 
which  would  burst  the  radiator  if  means  were  not 
taken  to  get  rid  of  the  excess.  It  also  serves  to 
permit  the  escape  of  any  steam  generated  in  the 
engine  jackets  with  the  engine  in  operation. 
The  amount  of  cooling  surface  of  the  radiator 


Fig.  118-B.     Hopper  cooling  on  Mogul  10-20. 

and  the  water  capacity  of  the  system  have  been 
so  proportioned  to  the  amount  of  heat  it  is  nec,es- 
sary  to  get  rid  of  as  to  maintain  the  engine  cylin- 
ders at  or  near  their  proper  working  temperature 
at  all  times. 

In  Figure  118-B  is  pictured  a  Mogul  10-20 
engine  equipped  also  with  a  thermo-syphon  sys- 
tem, but  of  very  much  simpler  design.  As  a 
matter  of  fact,  it  consists  simply  of  a  large  box 
or  hopper  surrounding  the  single-cylinder  of  this 
engine  and  which  takes  the  place  of  the  water 
jacket.  This  box  is  filled  with  water  and  serves 


Cooling.  183 

at  once  as  water  jacket,  water  tank  and  radiator. 
The  heated  water  simply  rises  to  the  top  of  the 
hopper  and  is  cooled  on  contact  with  the  air. 
The  capacity  of  the  hopper  is  comparatively  large 
so  that  fairly  good  cooling  is  obtained;  no  fan 
or  forced  draught  is  used. 

While  the  simple  hopper  system  is  well  adapted 
to  function  perfectly  on  such  low-powered  en- 
gines as  the  one  described  above,  when  we  come 


Fig.  119.     Pump  system  on  Aultman-Taylor. 

to  engines  of  high  power  more  adequate  means 
of  cooling  must  be  provided.  As  a  matter  of 
fact,  at  the  present  time  the  manufacturers  who 
are  relying  on  thermo-syphon  circulation  of  the 
cooling  water  are  greatly  in  the  minority.  Most 
tractor  engineers  feel  that  an  engine  running 
constantly ,  at  nearly  full  load  like  the  tractor 
engine,  and  where  temperatures  are  bound  to  be 
high,  needs  forced  water  circulation  quite  as  well 


184  Tractor  Engines. 

as  forced  oil  circulation,  and  the  result  is  that 
pump  cooling  is  coming  more  and  more  to  the 
fore. 

The  pump  system  differs  from  the  simpler 
thermo-syphon  system  in  one  particular  only. 
That  is  in  the  employment  of  a  pump — generally 
of  the  centrifugal  or  impeller  type — to  draw  the 
water  from  the  bottom  of  the  radiator  and  force 
it  through  the  cylinder  jackets.  The  centrifugal 
pump  is  employed  because  of  its  simplicity — it 
being  devoid  of  valves  and  checks — and  the  fact 
that  in  case  of  pump  failure  the  pump  offers  no 
impediment  to  the  circulation  of  the  water  by  the 
thermo-syphon  system,  so  that  the  engine  will 
be  reasonably  well  cooled.  Figure  119  shows 
the  pump  system  applied  to  a  typical  tractor,  the 
Aultman-Taylor. 

There  are  two  other  details  in  connection  with 
tractor  engine  cooling  that  it  is  well  to  note. 
The  first  is  the  employment  of  oil  in  the  cooling 
system  instead  of  water,  which- is  carried  out 
in  the  case  of  some  of  the  larger  Rumely  jobs; 
and  the  second  is  the  employment  of  a  water 
temperature  regulator  for  maintaining  the  water 
jackets  always  at  uniform  temperature  at  which 
the  fuel  is  best  handled,  a  practice  which  is  being 
introduced  by  the  Case  people  and  which  closely 
follows  what  has  been  found  best  in  automobile 
practice. 

The  use  of  oil  in  the  Rumelys  determines 
slightly  higher  cylinder  jacket  temperatures  than 
can  be  maintained  with  water  because  of  its  com- 
paratively low  boiling  point,  bringing  the  cylin- 
der temperature  up  to  a  point  which  is  practically 
the  ideal.  At  the  same  time,  the  oil  being  non- 
freezing  at  any  climatic  temperatures  encoun- 
tered in  this  country  at  least,  there  is  not  the 
slightest  need  of  draining  the  engine  cooling 


Cooling. 


185 


system  during  the  cold  weather  and  no  danger 
of  freezing  and  damaging  the  mechanism. 

The  device  used  on  the  Case  for  temperature 
control  is  a  simple  little  thermostat  which  regu- 
lates a  by-pass  valve,  as  shown  in  Figure  120. 
The  thermostat  itself  comprises  a  little  metal 
cylinder,  corrugated  to  make  it  flexible  and  ex- 
tensible as  to  length,  to  one  end  of  which  is  at- 
tached the  rod  which  actuates  the  by-pass  valve. 
This  cylinder  is  half  filled  with  a  very  volatile 
liquid  which  when  heated  expands,  creating  suf- 
ficient pressure  within 
the  cylinder  to  cause 
it  to  elongate,  moving 
the  rod  and  actuating 
the  valve. 

It  will  be  seen,  by 
reference  to  the  fig- 
'ure,  that  the  circulat- 
ing system  between 
the  engine  jackets  and 
the  radiator  is  "short- 
circuited"  by  a  by-pass 
pipe  and  the  thermo- 
stat cylinder  is  placed 
in  this  pipe.  The  ar- 
rangement is  such 
that  when  the  water 


FIG.  1 2O 


Fig.    120.      Syphon  regulator 
showing  path  of  circulation. 


is  cold,  the  thermostat  closes  the  passage  from 
the  radiator  to  the  engine  pump  and  opens 
the  by-pass  pipe  into  the  pump  intake  so  that 
the  water  does  not  circulate  through  the 
radiator  at  all,  but  simply  passes  through  the 
by-pass. 

Naturally,  there  being  only  a  slight  amount 
of  water  in  circulation,  it  heats  up  very  quickly 
and  the  engine  attains  its  normal  operating  tem- 
perature in  no  time.  As  the  water  heats  up,  the 


186  Tractor  Engines. 


thermostat  expands  and  allows  more  and  more 
cool  water  to  be  drawn  into  the  system  from 
the  radiator;  and  it  is  so  set  that  it  will  propor- 
tion the  feed  between  the  two  in  such'  a  manner 
as  to  feed  water  at  a  constant  temperature  to 
the  engine  throughout  the  day  and  quite  regard- 
less of  operating  conditions  and  loads  carried. 


CHAPTER  VIII. 

Care  of  the  Cooling  System. 

Any  Leaks  That  Develop   in  the  Water  System 
Should  be  Stopped  Immediately. 

IF  leaks  are  at  the  hose  joints,  tightening  the 
clamps  or  replacing  the  rubber  hose  with  new 
hose  will  effect  a  cure.  The  hose  should  be  re- 
placed every  season  with  new  hose  anyway, 
because  the  action  of  the  hot  water  tends  to  rot 
it,  causing  the  inner  lining  to  peel  off,  and  the 
circulation  of  the  peelings  will  carry  them,  in 
time,  to  the  top  header  of  the  radiator,  where 
they  are  likely  to  block  one  or  more  of  the  tubes, 
causing  partial  stoppage  of  the  circulation. 

From  time  »to  time  the  drain  cock  provided  at 
the  lowermost  point  in  the  radiator,  where  the 
water  passes  out  to  the  cylinder  jackets,  should 
be  opened  and  the  water  drained  from  the  sys- 
tem ;  the  system  should  be  flushed  out  with  fresh 
water,  which  will  have  the  effect  of  cleaning  out 
the  rust  and  any  sediment  due  to  the  use  of 
hard  water.  It  is  well,  once  in  every  month,  to 
put.  a  pound  of  washing  soda  into  the  radiator 
and  leave  it  there  for  a  day  .or  so,  permitting  the 
free  circulation  of  the  hot  soda  solution.  This 
will  free  any  scale  formed  on  the  inside  walls  of 
the  cylinder  jackets  and  in  the  radiator  itself  as 
a  result  of  the  use  of  hard  water,  and  will  also 
help  loosen  any  accumulation  of  rust ;  the  system 
should  then  be  thoroughly  flushed  out,  preferably 
by  removing  the  hose  connections  and  turning  a 
hose  first  through  the  radiator  and  then  through 

(187) 


188  Tractor  Engines. 


the  engine  jackets.  This  will  carry  off  any  sedi- 
ment and  leave  the  system  perfectly  clean. 

The  fan  belt  should  be  kept  perfectly  tight  by 
means  of  the  adjusting  screw  provided  in  the  fan 
bracket.  Take  up  the  slack  in  the  fan  belt  until 
the  fan  begins  to  drag  when  turned  by  hand. 

There  are  two  gaskets,  one  on  the  inlet  nipple 
flange  and  the  other  on  the  outlet  nipple  flange, 
to  which  the  connections  to  the  radiator  are 
attached,  which  will  leak  occasionally  unless  the 
stud  screws  holding  them  to  the  cylinder  castings 
are  drawn  up  tightly.  Leakage  of  water  from 
the  cylinder  head  gasket  should  be  corrected  im- 
mediately by  drawing  up  on  the  hold-down  bolts 
by  means  of  which  the  head  casting  is  fastened 
to  the  cylinder  block,  which  will  have  the  effect 
of  compressing  the  gasket  and  stopping  the  leak. 

Never  put  any  solid  or  any  liquid  containing 
a  solid  substance  in  the  radiator  to  stop  leakage. 
There  are  several  radiator  compounds  on  the 
market  intended  for  this  purpose,  which  are 
liquids  of  a  special  nature,  which  solidify  or  get 
gummy  when  they  are  mixed  with  warm  water 
and  brought  into  contact  with  the  air.  These 
substances  are  perfectly  safe  for  use  in  the  cool- 
ing system  to  correct  small  leaks,  and  they  will 
actually  act  to  prevent  the  formation  of  scale  at 
the  same  time,  when  used  in  accordance  with 
the  manufacturer's  directions. 

Overheating  of  the  engine  as  evidenced  by 
boiling  of  the  water  and  poor  operation  of  the 
motor  as  a  whole  may  be  caused  by  a  variety  of 
troubles.  The  presence  of  excessive  carbon  de- 
posit in  the  combustion  chamber  and  on  top  of 
the  pistons  will  cause  it,  the  cure  being  to  remove 
the  carbon  as  directed  in  a  previous  chapter. 

Racing  the  engine  is  a  frequent  cause;  run- 
ning with  the  spark  retarded;  poor  spark;  in- 


. 


Care  of  the  Cooling  System.       189 

sufficient  oil,  use  of  poor  oil  or  the  use  of  oil 
of  a  grade  unsuited  to  the  engine  will  cause  over- 
heating; improper  carburetor  adjustment,  giving 
either  too  lean  or  too  rich  a  mixture  and  thereby 
causing  slow  burning,  which  exposes  a  greater 
area  of  the  cylinder  walls  to  the  heat ;  fan  blades 
bent,  belt  broken  or  slipping;  improper  circula- 
tion due  to  clogged  or  jammed  radiator  tubes, 
leaky  connections  or  too  little  water  in  system. 

The  correction  for  most  of  these  is  apparent 
or  has  already  been  explained.  Those  having 
to  do  with  the  ignition  system  will  be  explained 
fully  in  a  later  chapter  dealing  with  this  impor- 
tant system. 

The  repair  of  a  leaky  radiator,  provided  it  is 
not  badly  broken  by  a  smashup  or  some  similar 
mishap,  is  a  job  that  is  best  left  to  a  mechanic 
who  has  specialized  in  work  of  this  sort  unless 
the  man  undertaking  the  job  has  had  quite  some 
experience  in  the  manipulation  of  soldering  tools. 
The  first  thing  to  do  is  to  remove  the  radiator 
from  the  tractor,  which  is  done  by  disconnecting 
the  hose  connections  to  the  engine  and  undoing 
the  bolts  which  fasten  the  radiator  brackets  to 
the  frame. 

With  the  radiator  off,  the  next  step  is  to  locate 
the  leak  or  leaks.  This  is  done  by  plugging  up 
the  inlet  and  outlet  passages  of  the  radiator, 
using  large  cork  stoppers  if  they  can  be  had  of 
ample  size,  or  potatoes  in  case  stoppers  are  not 
handy.  Then  with  a  tire  pump,  force  air  into 
the  radiator  through  the  overflow  pipe,  at  the 
same  time  submerging  the  radiator  in  a  tub  of 
water.  The  bubbles  caused  by  the  escaping  air 
will  indicate  the  place  where  the  radiator  is  leak- 
ing; it  should  be  marked  for  identification  when 
the  radiator  is  removed  from  the  water.  Next 
place  the  radiator  on  a  work  bench  and  heat  the 


190 


Tractor  Engines. 


tubes  around  the  leak  with  a  blow-torch.  When 
they  are  just  a  little  hotter  than  the  boiling  point 
of  water,  ordinary  acid  soldering  solution,  made 
by  treating  muriatic  (hydrochloric)  acid  with 
pure  zinc,  is  poured  through  the  fins  all  over 
the  leaky  tubes  to  thoroughly  clean  their  surfaces. 
Then  melt  a  ladleful  of 
solder,  which  should  be 
ordinary  half  in  half 
plumbers'  sol- 
der, and  after 
blocking  the 
radiator  up 
from  the  bench 
sufficiently  to 
be  able  to  hold 
another  ladle 
beneath  it,  pour 
the  solder 
through  the 
fins  and  over 
the  tubes,  catch- 
ing it  in  the 
empty  ladle,  as 
shown  by  the 
sketch  (Figure 
121).  Then 
turn  the  radia- 
tor over  and 
repeat  the  op- 
eration, pour- 
ing through  in 
the  opposite  direction.  Apply  more  of  the  sol- 
dering solution  and  heat  once  again  with  the 
torch  until  the  solder  melts  and  runs  into  the 
leaks,  sealing  them  against  further  leakage.  Be- 
fore putting  the  radiator  back  on  the  tractor,  it 
is  best  to  test  it  once  again  to  make  sure  that 


Fig.   121.     Method  of  repairing  vertical 
tube  radiator. 


Care  of  the  Cooling  System.       191 

all  the  leaks  have  been  soldered  up.  In  case  a 
tube  is  jammed,  the  best  plan  is  to  cut  it  off 
an  inch  above  and  below  the  clotiire  and  sweat 
a  new  piece  of  tube  of  the  correct  length  and 
diameter  in  place  of  the  piece  that  has  been 
removed. 

During  winter  weather  some  precautions  must 
be  taken  to  protect  the  radiator  from  freezing, 
especially  when  the  tractor  is  left  standing  with 
the  engine  shut  off.  Freezing  of  the  water  in 
the  radiator  is  bound  to  cause  the  tubes  to  burst 
and  leak,  and  if  the  water  freezes  in  the  engine 
jackets,  the  jacket  itself  will  burst  in  nine  cases 
out  of  ten  and  it  will  be  necessary  to  have  it 
welded  to  effect  a  repair.  In  some  cases  of 
radiator  freezing  the  rupture  will  be  so  bad  that 
it  will  be  necessary  to  replace  the  radiator  with 
a  new  one.  It  is  well,  therefore,  to  take  the 
simple  precautions  necessary  to  guard  against 
such  a  contingency. 

If  the  tractor  is  used  only  occasionally  during 
the  winter  months,  the  best  plan  is  to  pour  hot 
water  into  the  cooling  system  when  starting  out. 
This  will  facilitate  starting  of  the  engine.  Cover 
the  lower  portion  of  the  radiator  with  a  piece  of 
cardboard,  so  that  the  cooler  water  at  the  bottom 
of  the  radiator  will  not  freeze.  At  the  end  of 
the  day,  drain  the  cooling  system  thoroughly  by 
opening  the  drain  cock,  letting  the  engine  idle 
while  the  water  is  running  out,  in  order  to  pro- 
vide sufficient  heat  to  dry  the  jackets  thoroughly. 

If  the  tractor  is  used  a  great  deal  throughout 
the  winter,  the  best  plan  is"  to  use  a  non-freezing 
solution  in  the  cooling  system.  There  are  several 
substances  which  can  be  mixed  with  the  cooling 
water  and  which  will  have  the  desired  effect  of 
lowering  its  freezing  point.  Quite  the  most  com- 
monly used  is  wood  or  denatured  alcohol.  A  20 


192  Tractor  Engines. 


per  cent  solution  of  alcohol  and  water  does  not 
freeze  until  a  temperature  of  15  degrees  F.  is 
reached;  a  30  per  cent  solution  freezes  at  8  de- 
grees below  zero,  and  a  50  per  cent  solution  at  15 
degrees  below.  Glycerine  and  calcium  chloride 
are  sometimes  used  instead  of  the  alcohol. 

The  trouble  with  alcohol  is  that  its  boiling 
point  is  quite  a  bit  lower  than  that  of  water,  so 
that  it  evaporates  quickly,  and  it  is  therefore 
necessary  to  replenish  the  supply  from  time  to 
time  in  order  to  guard  against  freezing.  The 
glycerine,  on  the  other  hand,  attacks  the  rubber 
hose  connections,  causing  swelling  and  peeling, 
while  the  calcium  chloride  forms  an  alkali  solu- 
tion which  sets  up  electrolytic  action  between 
the  copper  radiator  tubes  and  the  solder,  causing 
them  to  corrode,  which,  of  course,  is  not  at  all ' 
desirable.  There  are  several  compounds  on  the 
market  intended  to  prevent  freezing  of  the  cool- 
ing water  and  which  are  said  to  be  free  from 
any  of  these  defects. 

During  the  last  year  or  so  it  has  become  quite 
common  practice  to  drain  the  water  from  the 
cooling  system  and  fill  it  up  with  kerosene  during 
the  winter  months.  This  practice  will  work  out 
to  advantage  in  cases  where  the  tractor  is  used 
often  but  not  driven  very  hard  and  is  stopped 
frequently.  For  very  hard  plugging  the  use  of 
kerosene  is  not  to  be  recommended,  for  the  simple 
reason  that  its  specific  heat — its  capacity  to  ab- 
sorb heat — is  only  about  one-half  that  of  water 
while  its  conductivity  of  heat  is  only  about  one- 
third  that  of  water.  It  is  evident  that  it  has  not 
the  capacity  for  carrying  away  enough  of  the 
heat  from  the  cylinders  to  provide  for  proper 
cooling  if  the  engine  is  run  all  out  for  long  in- 
tervals. 


CHAPTER  IX. 

Ignition  System. 

How  the  Spark  Is   Produced   and  Controlled  to 
Obtain  the  Desired  Results. 

IN  order  to  ignite  the  mixture  in  the  cylinder 
of  the  engine,  a  spark  which  is  hot  enough  to 
raise  the  gas  adjacent  to  its  critical  temperature 
and  thereby  set  fire  to  it  is  essential.  The 
simplest  way  of  producing  a  spark  in  the  cylin- 
der of  an  engine  at  exactly  the  time  required  to 
ignite  the  mixture  is  to  make  use  of  the  electric 
current,  which  in  its  action  is  practically  in- 
stantaneous. 

To  thoroughly  comprehend  the  operation  of 
the  ignition  system  we  must  start  right  at  the 
beginning  and  learn  something  of  the  nature  of 
the  electric  current  and  its  generation.  We  all 
know  what  a  magnet  is — a  common  horseshoe 
magnet  such  as  the  schoolboy  uses  for  a  play- 
thing. Let  us  consider  its  properties  for  a 
minute.  It  is  nothing  more  than  a  simple  bar  of 
steel,  bent  in  the  shape  of  a  horseshoe  and  mag- 
netized, and  it  has  the  property  of  attracting 
things  made  of  iron  and  steel,  and  to  a  lesser 
degree,  manganese  and  nickel.  More  careful 
examination  of  the  properties  of  the  magnet  re- 
veal that  the  action  of  the  two  ends  is  not  the 
same  and  we  have  come  to  know  one  end  as  the 
North  or  Positive  end  of  the  magnet  and  the 
other  one  the  South  or  Negative  pole.  We  have 
.discovered  that  issuing  from  the  North  pole 
there  are  certain  lines  of  magnetic  force  which 

(193) 


194 


Tractor  Engines. 


spread  apart  somewhat  in  the  air  and  then  con- 
verge again  and  enter  the  South  pole  of  the  mag- 
net. It  is  these  lines  of  magnetic  force — their 
exact  nature  is  quite  unknown  to  us — which  give 
the  magnet  the  property  of  attracting  substances 
susceptible  to  magnetic  influence. 

Let  us  consider  that  we  have  such  a  magnet 
(Figure  122)  and  that  it  is  a  very  strong  one, 
which  means  that  there  are  a  whole  lot  of  mag- 
netic lines  of  force  crowded  into  a  very  small 
space  between  the  two  poles.  Let  us  suppose, 
also,  that  we  have  a  loop  of  wire  like  a  hoople 


!/ 


N 


^l*N 

t    I  *\ 


'NO  N 

» \v 


OAR 


MAGNET 
AND 

or    F-ORCE: 


Fig.  122.  Typical  magnets  illus- 
trating lines  of  magnetic  force  or  the 
magnetic  field  set  up  between  the 
poles. 


OF"     FOKCf. 


— a  complete  circle,  in  other  words.  We  hold 
the  hoople  in  one  hand  and  the  magnet  in  the 
other  and  we  move  the  loop  in  so  that  the  wire 
on  one  side  of  the  loop  enters  between  the  poles 
of  the  magnet  and  crosses  or  cuts  every  one  of 
the  lines  of  magnetic  force  traveling  between 
these  poles.  While  we  are  actually  moving  the 
wire  through  the  field  of  magnetic  force  and 
actually  cutting  lines  of  force,  there  is  a  current 
of  electricity  generated  in  the  wire  and  flowing- 
through  it.  And  furthermore,  the  faster  we  cut 


Ignition  System.  195 

the  lines  of  force — that  is,  the  greater  number  of 
lines  cut  in  a  given  interval  of  time — the  greater 
will  be  the  strength  of  the  current. 

Now  let  us  suppose  that  we  have  carried  the 
loop  all  the  way  in  and  have  reversed  the  motion 
and  are  bringing  it  out  again;  it  is  then  cutting 
the  lines  of  force  in  the  opposite  direction,  and 
while  it  is  actually  moving,  there  is  a  current 
generated  in  the  wire.  But  this  time,  due  to  the 
reversal  of  the  direction  in  which  the  lines  of 
force  are  cut,  the  current  flows  in  the  opposite 
direction  to  which  it  was  flowing  in  the  first 
instance.  If  now  we  keep  the  coil  of  wire  mov- 
ing in  and  out,  we  will  have  a  current  flowing 
as  long  as  there  is  movement,  and  it  will  reverse 
itself  each  time  the  direction  of  motion  is  re- 
versed and  we  have  what  we  term  an  "alter- 
nating" current.  If  it  were  always  flowing  in 
the  same  direction  we  would  call  it  a  direct 
current. 

The  important  thing  to  bear  in  mind  is  that 
there  must  be  a  complete  circuit  for  the  current 
to  flow  through — if  we  open  the  loop  of  wire 
the  current  stops  immediately,  regardless  of  the 
movement  of  -the  coil — and  that  the  current  flows 
only  while  the  lines  of  magnetic  force  are  actu- 
ally being  cut.  It  makes  no  difference  whether 
we  move  the  magnet  or  move  the  coil;  provided 
the  motion  is  such  that  lines  of  force  are  cut 
by  the  wire,  we  set  up  a  current  of  electricity  in 
the  loop.  It  is  a  fact,  also,  that  both  can  be  held 
still  and  by  decreasing  and  increasing  the- 
strength  of  the  magnet,  we  cause  the  lines  of 
force  themselves  to  move,  and  in  so  moving  to 
cut  the  coil  -of  wire  and  get  the  same  effect — 
but  always  to  get  a  current  lines  of  force  must 
be  cut  by  the  wire  loop.  This  latter  principle 
should  be  borne  distinctly  in  mind,  as  it  is  all- 


196  Tractor  Engines. 

important  to   a  thorough  understanding  of   the 
ignition  system. 

The  current  generated  by  the  simple  apparatus 
we  have  described  would  be  so  slight  as  to  be 
imperceptible  and  incapable  of  measurement 
except  by  the  finest  of  instruments.  Since  the 
current  strength  depends  upon  the  number  of 
lines  of  force  which  we  cut  in  a  given  interval 
of  time,  it  is  obvious  that  there  are  three  ways 
of  increasing  its  strength: 

1.  Increase   the   speed   of    the   moving   part, 
whether  it  is  the  magnet,  the  coil  or  the  field 
itself. 

2.  Increase  the  number  of  lines  of  force,  or 
in  other  words,  the  strength  of  the  magnet. 

3.  Increase  the  number  of  turns  of  wire  on 
the  coil,  for  it  is  obvious  that  two  loops  will  cut 
twice  as  many  lines  of  force  in  a  given  interval 
of  time  as  one  loop. 

Here  we  have  concretely  stated  the  elements 
of  a  practical  dynamo.  If  we  employ  field  mag- 
nets of  great  strength,  and  if  we  employ  a  large 
number  of  turns  of  wire  on  the  revolving  arma- 
ture, and  if,  furthermore,  we  rotate  the  armature 
at  high  speed,  we  produce  a  current  at  fairly 
high  pressure  or  voltage. 

But  even  so,  it  takes  very  high  electrical  pres- 
sure to  force  a  current  to  jump  over  even  the 
smallest  air  gap.  If  the  wire  in  a  circui't  be 
broken  and  the  ends  separated  by  even  the  slight- 
est distance,  for  instance,  the  current  is  imme- 
diately interrupted  and  does  not  jump  the  gap 
and  produce  a  spark  except  at  the  very  instant 
when  the  break  occurs.  And  we  can  bring  the 
two  ends  together  just  as  close  as  we  care  to, 
without  rhaking  them  actually  touch,  and  the  cur- 
rent flow  will  not  be  re-established. 

In  order  to  get  the  current  to  jump  a  gap  of 


Ignition  System.  197 

i 

sufficient  length  to  ignite  the  mixture  in  our 
cylinders,  therefore,  we  have  to  resort  to  special 
means  to  increase  the  pressure  far  and  above 
the  voltage  that  can  be  created  directly  by  a 
dynamo  such  as  we  have  described  above  of  a 
size  to  be  applicable  to  the  tractor  engine.  There 
are  two  methods  of  accomplishing  this.  The  first 
is  to  make  use  of  an  induction  coil  or  a  trans- 
former coil,  and  its  operation  will  not  be  hard 
to  comprehend,  provided  we  have  grasped  the 
fundamental  principles  of  the  dynamo  just 
described. 

Let  us  go  back  once  again  to  our  loop  of  wire 
and  consider  that  we  have  current  flowing 
through  it.  It  is  a  peculiar  fact  that  whenever 
current  flows  through  a  conductor  such  as  a  wire, 
all  around  that  wire  we  create  a  field  of  mag- 
netic lines  of  force  exactly  as  we  have  lines  of 
magnetic  force  issuing  from  the  magnet.  Any 
wire  with  electric  current  flowing  through  it, 
therefore,  is  in  reality  a  magnet,  and  the  strength 
of  the  magnet  will  depend  upon  the  strength 
of  the  current  flowing  through  it,  and  the  num- 
ber  of  turns  of  wire  on  the  coil.  Now,  if  we  coil 
the  wire  up  into  a  helix,  which  is  a  coil  like  an 
exhaust  valve  spring,  having  all  the  layers  in- 
sulated from  each  other,  and  inside  that  coil  we 
place  a  core  made  of  soft  iron  wire,  the  lines  of 
magnetic  force  engendered  by  the  passage  of  the 
current  will  flow  through  that  core  and  one  end 
will  become  a  North  pole  and  the  other  a  South 
pole  and  the  lines  of  force  from  the  North  pole 
will  bulge  out  around  the  coil  on  all  sides  and 
bend  in  again  to  meet  the  South  pole  while  cur- 
rent is  flowing  through  that  coil. 

If  we  pass  more  current  through  the  coil  the 
lines  of  force  will  bulge  out  further,  like  a  barrel, 
and  if  we  suddenly  stop  the  flow  by  breaking 


198  Tractor  Engines. 

the  circuit,  they  will  very  quickly  collapse  in 
ward  the  coil  and  then  stop  flowing.  But  the 
big  point  to  bear  in  mind  is  that  varying  the 
strength  of  the  field  by  making  and  breaking  the 
circuit  will  cause  that  magnetic  field  to  move 
quickly  away  from  and  toward  the  coil. 

Now  let  us  say  that  we  have  such  a  coil  with 
one  end  attached  to  the  dynamo  terminal  or  to 
one  pole  of  a  battery  of  dry  cells  and  the  other  end 
grounded  so  that  the  circuit  is  complete.  And 
supposing  on  top  of  that  coil,  but  fully  insulated 
from  it,  we  wind  another  coil  consisting  of  a 
very  large  number  of  turns  of  very  fine  wire 
and  we  fasten  one  end  of  this  second  coil  to  the 
spark  plug  terminal  and  the  other  end  we  ground. 
Then  we  have  substantially  a  complete  circuit, 
the  only  break  in  it,  provided/  the  plug  is  screwed 
into  place  in  the  cylinder,  is  the  spark  gap  in 
the  plug.  By  "grounding,"  we  mean  attaching 
the  wire  to  the  metal  part  of  the  machinery  so 
that  the  machine  itself,  such  as  the  engine  frame, 
becomes  part  of  the  circuit.  All  ignition  circuits 
are  grounded  in  this  way. 

Supposing  now  that  we  have  the  dynamo  run- 
ning so  that  current  is  flowing  through  the  first 
coil,  which  we  will  call  our  primary  coil ;  then 
the  magnetic  field  set  up  around  this  primary  coil 
will  completely  envelop  the  second  coil,  which 
we  will  call  our  secondary  coil.  If  now  we  sud- 
denly break  the  dynamo  or  primary  circuit,  caus- 
ing a  sudden  stoppage  of  the  current  flow,  the 
magnetic  field  issuing  from  the  primary  circuit 
will  suddenly  collapse,  cutting  all  of  the  very 
many  turns  of  wire  on  the  secondary  coil  so  that 
we  have  an  abundance  of  lines  of  force  moving 
at  very  rapid  rate  and  cutting  a  great  number 
of  wires — every  condition  favorable  for  the  pro- 
duction of  high  electrical  pressure,  and  conse- 


Ignition  System. 


199 


quently  we  can  take  from  the  coil,  just  at  the 
instant  the  primary  circuit  is  broken,  current  at 
sufficiently  high  pressure  to  jump  the  spark  plug 
gap  and  return  to  the  grounded  end  of  the 
secondary  circuit  through  the  metal  parts  of  the 
engine. 

This  arrangement  of  the  primary  and  second- 
ary circuits  is  shown  in  detail  in  Figure  123,  ex- 
cept that  a  battery  of  dry  cells  is  substituted  for 
the  dynamo  in  order  to  make  the  operation  clear. 


Fig.  123.  Construction  of  conventional  induction  coil  used  for 
ignition  purposes. 

The  primary  circuit  is  represented  by  the 
heavy  line  and  the  arrows  indicate  the  direction 
of  flow.  Considering  the  switch  at  E  and  F 
closed,  the  current  starts  and  flows  through  the 
timer,  which  is  also  considered  to  be  making  con- 
tact and  completing  the  circuit,  to  the  binding 
post  M.  Thence  through  the  contact  C  to  spring 
contact  B  and  through  the  heavy  coil  around  the 
soft  iron  core  and  out  to  the  grounded  terminal 


200  Tractor  Engines. 

U.  Thence  through  the  metal  parts  back  to  the 
grounded  terminal  of  the  battery  at  I.  It  was 
said  that  when  the  current  is  flowing  through  the 
primary,  the  core  really  becomes  a  magnet.  Such 
being  the  case,  it  attracts  the  little  piece  of  soft 
iron  D  mounted  on  the  contact  spring  A  and  in 
pulling  it  it  separates  the  contacts  B  and  C  and 
breaks  the  circuit.  The  magnetic  field  immedi- 
ately disappears  and  the  spring  draws  the  arma- 
ture back  and  the  contacts  again  meet  and  re- 
establish the  circuit  and  the  same  thing  occurs  all 
over  again.  The  spring  keeps  on  vibrating, 
alternately  making  and  breaking  the  circuit,  first 
building  up  and  then  destroying  the  magnetic 
field  around  the  primary  coil,  keeping  it  in  con- 
stant agitation  so  that  it  is  continually  causing 
lines  of  magnetic  force  to  be  cut  at  a  very  rapid 
rate  and  consequently,  in  the  secondary  coil 
shown  in  lighter  line  on  top  of  the  primary, 
there  is  generated  a  current  at  very  high  pressure 
or  voltage. 

From  one  of  the  secondary  terminals,  the  plug 
cable  leads  to  the  spark  gap  X,  which  in  the  case 
of  the  ignition  coil  is  the  terminal  on  the  spark 
plug,  while  the  other  secondary  terminal  is 
grounded  so  that  the  current  jumps  the  gap  to 
the  grounded  terminal  on  the  spark  plug  and 
makes  its  way  back  through  the  metal  parts  of 
the  engine  to  the  grounded  secondary  spark  coil 
terminal.  It  will  be  understood  from  what  we 
have  said  of  the  nature  of  the  secondary  current, 
that  extra  precautions  must  be  taken  to  prevent 
its  escape,  since  its  pressure  is  so  high  that  un- 
less well  insulated  it  will  pass  to  the  metal  parts 
of  the  tractor  and  complete  the  secondary  circuit 
without  bothering  to  cross  the  spark  plug  gap, 
and  in  such  a  case  the  cylinder  will  miss  fire, 
since  there  is  no  spark  occurring  in  it  to  set  fire 


Ignition  System.  201 

to  the  mixture.  For  this  reason,  the  secondary 
wiring  leading  from  the  high-tension  terminals 
of  spark  coils  to  the  spark  plug  terminals  are 
made  of  very  heavily  insulated  ignition  wiring 
and  care  should  be  taken  in  case  replacement  is 
necessary  to  use  secondary  wiring  for  the  plug 
cables.  The  primary  wiring,  on  the  other  hand, 
which  carries  the  current  at  low  pressure,  need 
not  be  so  ^leavily  insulated,  since  the  voltage  is 
not  sufficient  to  cause  it  to  jump  an  air  gap  or 
break  down  the  insulation. 

When  we  start  the  flow  of  electric  current,  it 
acquires  a  certain  amount  of  momentum  in  a 
manner  somewhat  similar  to  bodies  which  are  in 
movement.  When  we  come  to  stop  it  suddenly 
it  offers  some  resistance  and  tends  to  persist  in 
its  forward  movement.  If,  then,  we  open  the 
contact  points  B  and  C,  the  primary  current  flow- 
ing through  the  circuit,  due  to  this  momentum, 
tends  to  keep  on  flowing  and  this  continued  flow 
is  evidenced  as  a  blue  spark  across  the  air  gap 
which  is  formed  between  the  points.  The  spark 
is  undesirable  from  two' standpoints.  In  the  first 
place,  it  causes  burning  and  pitting  of  the  c6n- 
tact  points,  and  in  order  to  resist  the  heat  of 
the  spark  it  is  necessary  that  these  points  be 
made  of  heat-resisting  metal.  In  days  before  the 
war,  platinum  was  the  metal  invariably  used,  but 
owing  to  its  scarcity  at  present,  tungsten  and 
tungsten  alloys  are  being  used  with  very  good 
results. 

The  second  bad  effect  of  this  spark  across  the 
points  is  that  just  so  long  as  a  spark  is  present, 
current  must  be  flowing,  as  it  is  the  current 
which  is  the  cause  of  the  spark.  It  will  be  re- 
membered that  to  set  up  an  intense  current  in  the 
secondary  we  said  it  was  necessary  to  cut  the 
greatest  number  of  lines  of  force  possible  with 


202  Tractor  Engines. 


the  coil  in  the  shortest  interval  of  time —  in  other 
words,  it  is  necessary  to  destroy  the  primary 
magnetic  field  as  quickly  as  possible.  It  is  de- 
sirable, therefore,  to  eliminate  this  spark  so  that 
the  current  in  the  primary  circuit  will  stop  short 
and  the  field  will  be  instantly  destroyed. 

To  do  this,  and  eliminate  the  spark,  we  make 
use  of  a  special  little  device  called  a  condenser, 
which  is  connected  up  to  both  of  the  contact 
points  on  the  circuit  breaker,  so  that  when  the 
points  open  it  in  reality  bridges  the  gap  left 
between  them.  It  is  indicated  by  the  letter  L  in 
Figure  123.  The  condenser  is  composed  of  alter- 
nate layers  of  tinfoil  and  paraffin  paper  which 
serves  to  insulate  one  tinfoil  layer  from  the  next. 
Every  second  lay^er  of  tinfoil  is  brought  out  on 
one  side  of  the  condenser,  all  being  fastened  to- 
gether and  connected  to  a  terminal,  and  every 
second  layer  is  treated  in  the  same  manner  on  the 
other  side  of  the  instrument,  so  that  one  terminal 
is  completely  insulated  from  the  other.  The  de- 
vice, therefore,  offers  no  path  for  the  current. 

It  has,  however,  the  singular  property  of  being 
able  to  absorb  electrical  current  and  the  amount 
it  will  absorb  depends  upon  the  area  of  the  tin- 
foil used  in  its  construction.  When  the  contact 
points  are  opened,  the  onrush  of  the  current,  due 
to  its  inertia,  causes  it  to  flow  into  the  condenser, 
charging  it,  and  checking  the  tendency  of  the 
current  to  flow  across  the  points  and  cause  a 
spark.  When  the  contact  points  come  together 
again,  the  condenser  is  discharged  through  the 
primary  circuit,  helping  to  establish  the  circuit 
again. 

To  use  a  crude  analogy,  it  acts  in  a  manner 
similar  to  the  air  dome  or  chamber  used  on  a 
fire  engine.  If  the  fireman  suddenly  turns  off 
the  hose  nozzle  with  the  pump  in  operation,  the 


Ignition  System.  203 

water,  due  to  its  inertia  and  the  action  of  the 
pump,  is  forced  into  this  air  chamber  compress- 
ing the  air  above  it.  If  this  chamber  were  nbt 
provided,  the  water  would  burst  the  hose  just  as 
in  the  electric  system  the  inertia  of  the  current 
will  cause  it  to  jump  the  gap  between  the  open- 
ing contacts  when  no  condenser  is  provided  to 
absorb  the  current.  When  the  fireman  opens  the 
nozzle  again,  the  air  pressure  forces  the  water 
out  of  the  dome  through  the  hose,  helping  to' 
re-establish  the  flow  of  water  and  give  a  good, 
strong  stream. 

We  find  that  with  a  plain  coil  without  a  con- 
denser, the  spark  is  very  weak — altogether  too 
weak  to  jump  the  plug  gap  in  the  engine  cylin- 
der and  that  sparking  at  the  circuit  breaker  soon 
causes  the  points  to  burn  and  wear  away.  With 
the  condenser  in  the  circuit,  'we  get  a  fine  hot 
spark  with  none  of  this  trouble. 

There  generally  is  a  separate  spark  coil  used 
for  each  cylinder.  They  are.  very  compact,  the 
condenser  being  embodied  right  in  the  coil,  which 
is  protected  with  a  wax  composition  insulation 
and  which  has  the  little  electromagnetic  circuit 
breaker  mounted  right  on  top  of  the  coil  unit. 
There  are  only  three  terminals  on  the  coil,  be- 
cause, since  one  end  of  the  primary  coil  and  one 
end  of  the  secondary  are  grounded  as  described 
above,  to  simplify  the  construction,  the  grounded 
ends  of  the  coils  are  connected  together  inside 
the  insulation  and  only  one  ground  wire  serving 
for  both  primary  and  secondary  coils  is  brought 
out  to  the  metal  contact.  , 

It  is  necessary,  of  course,  to'  pass  the  mag- 
netic current  through  the  proper  coil  at  exactly 
the  instant  the  spark  is  required  in  the  particular 
cylinder  which  is  at  the  top  of  its  compression 
stroke  and  ready  to  fire.  For  this  purpose  we 


204 


Tractor  Engines. 


use  a  little  rotary  switch  called  a  timer,  which 
is  mounted  on  the  front  end  of  the  camshaft  so 
that  the  rotary  contact  member  revolves  at  half 
the  speed  of  the  crankshaft.  The  timer  (Figure 
124)  consists  of  a  ring  of  fiber  insulating  material 
in  which  are  embedded  four  short  segments  of 
brass  mounted  diametrically  opposite  one  an- 
other. Contact  is  established  between  these  seg- 
ments and  four  screw  terminals  or  binding  posts 
mounted  on  the 
outside  of  the 
timer. 

The  rotary 
contact  m  e  m- 
b  e  r  comprises 
a  lever  fitted 
with  a  compar- 
atively large 
roller  at  one 
end,  the  lever 
being  pivoted 
to  a  fulcrum 
attached  to  the 
end  of  the  cam- 
shaft by  means 
of  a  screw 
thread  and  lock 
nut.  At  the 
other  end  of  the  lever  is  a  helical  spring  anchored 
to  a  projection  on  the  fulcrum  arm,  the  arrange- 
ment being  such  that  the  spring  keeps  the  roller 
constantly  in  contact  with  the  inner  side  of  the 
fiber  ring  on  which  are  placed  the  brass  contact 
segments.  The  ring  is  held  stationary,  although 
it  is  adapted  to  turn  through  a  short  arc,  so  that 
when  the  engine  is  in  operation  the  roller  makes 
one  complete  circuit  of  the  ring  for  every  two 
revolutions  of  the  crankshaft  and  makes  contact 


Fig.    124.      Construction    of   typical    timer 
or  commutator. 


Ignition  System.  205 

with  each  of  four  segments  once.  A  metal  cover 
provided  with  an  oiler  is  fitted  to  the  commuta- 
tor to  keep  out  the  dirt  and  keep  in  the  light 
machine  oil  which  is  used  for  lubrication. 

It  will  be  seen  that  the  rotary  contact  maker  is 
not  insulated  from  the  camshaft — in  other  words, 
it  is  "grounded"  to  the  engine.  Each  time  it 
makes  contact  with  one  of  the  segments,  there- 
fore, the  coil  to  which  this  segment  is  attached  is 
also  grounded,  so  that  the  primary  circuit  is 
completed,  current  flows  through  that  particular 
coil,  but  not  through  any  of  the  others,  since  they 
are  not  grounded  and  the  circuit  is  not  complete, 
and  the  circuit  breaker  vibrates  and  we  get  cur- 
rent from  the  secondary  coil  which  is  conducted 
from  the  proper  terminal  in  the  middle  row  of 
terminals  on  the  back  of  the  coil  box  to  the  spark 
plug  in  the  cylinder  ready  to  fire.  It  jumps  the 
gap,  ignites  the  mixture,  returns  through  the 
metal  of  the  engine  and  through  the  timer  to 
the  ground  wire  which,  it  will  be  remembered, 
is  attached  to  the  grounded  terminals  of  both 
primary  and  secondary  circuits. 

Figure  125  gives  a  cross-sectional  view  of  a 
typical  spark  plug  screwed  into  the  cylinder  and 
also  indicates  the  path  of  the  secondary  current. 
N  represents  the  high  tension  terminal  on  the 
coil  from  which  the  current  passes  immediately 
the  timer  establishes  contact  to  the  terminal  on 
top  of  the  plug.  It  then  flows  down  through 
the  central  electrode,  as  indicated  by  the  arrows, 
jumps  the  spark  gap — two  gaps  are  indicated  in 
the  plug  illustrated — to  the  grounded  electrode 
which  is  attached  to  the  spark  plug  shell.  As  the 
shell  is  screwed  into  the  metal  cylinder,  the  cur- 
rent is  grounded  and  travels  back  to  the  grounded 
secondary  coil  winding  through  the  metal  parts 
of  the  engine. 


206 


Tractor  Engines. 


The  plug  consists  of  an  outer  shell  of  steel  or 
brass  adapted  to  screw -into  the  plug  hole  in  the 
cylinder,  an  inner  insulator  generally  made  of 
porcelain,  special  stone  composition  or  mica  and 
through  which  runs  the  central  or  insulated  elec- 
trode, and  a  compression  nut  and  packing  or 
gasket  by  means  of  which  the  various  parts  are 


Fig.  125.     Construction  of  a  typical  spark  plug. 

held  together  so  as  to  correctly  insulate  the  cen- 
tral electrode  and  at  the  same  time  make  the 
construction  perfectly  gas-tight  and  prevent  loss 
of  compression.  The  illustration  shows  a  special 
type  of  plug  provided  also  with  an  outer  insu- 
lating shell,  adapted  to  keep  moisture  from  the 
main  insulator  and  thus  prevent  short-circuiting 
of  the  plug,  for  it  is  a  fact  that  with  the  high- 


Ignition  System.  207 

tension  secondary  current,  moisture  either  on  the 
plugs,  the  coil  or  the  wiring  will  result  in  the 
current  taking  the  easiest  way  back  to  ground 
and  it  will  become  short-circuited  and  will  fail 
to  pass  through  the  plug  and  across  the  spark 
gap  and  missing  will  be  the  result. 

To  go  back  to  the  case  of  the  burning  news- 
paper which  was  used  as  an  illustration  in  one  of 
the  previous  chapters :  if  we  light  one  corner  of 
it  with  a  match,  it  takes  some  little  time  for  the 
flame  to  spread  and  set  the  whole  paper  in  flames. 
In  the  mixture  in  the  cylinder  we  are  igniting  the 
gas  at  just  one  corner — in  the  little  cylinder 
pocket  in  which  the  valves  are  mounted,  to  be 
exact — and  it  takes  an  appreciable  interval  of 
time  for  the  entire  body  of  gas  to  become  ignited 
and  develop  its  greatest  heat  and  consequently 
the  greatest  pressure  on  top  of  the  cylinder.  In 
order  to  obtain  maximum  power  from  the  engine, 
it  is  necessary  that  we  should  apply  this  maxi- 
mum pressure  or  push  on  the  top  of  the  piston 
just  as,  or  very  shortly  after,  it  starts  on  its  down 
stroke.  If  we  have  a  slow-speed  engine,  the 
travel  of  the  piston  is  comparatively  slow,  and  if 
we  ignite  the  gas  just  as  the  piston  reaches  the 
top  of  its  stroke,  the  very  rapid  travel  of  the 
flame  results  in  our  obtaining  the  maximum 
pressure  very  nearly  at  the  top  of  the  stroke  and 
we  obtain  full  power. 

With  a  high-speed  engine,  however,  the  piston 
travel  is  exceedingly  fast,  and  if  we  wait  to  ignite 
our  gas  at  the  very  top  of  the  piston  travel  the 
piston  will  be  quite  some  distance  down  before 
the  flame  has  spread  all  through  the  mixture  and 
developed  the  maximum  pressure.  We  will  have 
only  a  portion  of  the  working  stroke  to  travel 
and  cannot,  therefore,  take  full  advantage  of 
the  pressure  we  have  developed;  moreover,  a 


208  Tractor  Engines. 

large  portion  of  the  cylinder  wall  will  be  ex- 
posed to  the  intensely  hot  gases  at  the  moment 
of  maximum  pressure,  and  as  a  result  we  will 
have  a  tendency  for  the  engine  to  overheat. 

We  overcome  this  condition  on  a  high-speed 
engine  by  a  little  dodge  which  we  call  advancing 
the  spark.  That  is,  we  cause  the  spark  to  occur 
in  the  cylinder  while  the  piston  is  still  coming  up 
on  the  compression  stroke,  and  the  amount  we 
advance  it  gives  just  sufficient  time  for  the  full 
expansion  of  the  gases  to  take  place  while  the 
piston  is  still  coming  up,  so  that  when  it  reaches 
the  top  we  have  developed  the  full  pressure,  and 
consequently  we  get  greater  power,  greater  speed 
and  a  cooler  running  engine. 

It  stands  to  reason  that  a  tractor  engine  is 
neither  a  high-speed  engine  nor  a  low-speed  one, 
but  is  a  variable  speed  engine,  partaking  of  the 
characteristics  of  both.  As  a  consequence,  we 
must  so  arrange  things  that  we  can  cause  the 
spark  to  occur  early  when  running  at  high  speed 
and  late  at  low  speed  to  get  the  best  results 
from  our  engine,  regardless  of  conditions.  And 
so  we  have,  on  the  modern  tractor  engine,  a  vari- 
able spark  controlled  by  a  spark  control  lever 
near  the  operator,  by  means  of  which  the  oper- 
ator can  cause  the  spark  in  the  'cylinders  to  occur 
at  the  proper  time  to  meet  the  conditions  called 
for  by  the  speed  of  the  engine. 

This  variation  is  brought  about  by  rotating  the 
body  of  the  timer  through  a  slight  arc,  this  being 
accomplished  by  means  of  rods  and  levers  at- 
tached to  the  spark  control  lever.  If,  for  in- 
stance, we  rotate  the  timer  body  in  a  clockwise 
direction  or  in  the  direction  opposite  to  the  rota- 
tion of  the  camshaft,  we  are  bringing  the  con- 
tacts up  to  meet  the  rotating  contact  maker  and 
the  contact  will  be  established  earlier  in  the 


Ignition  System.  209 

stroke — this  we  call  advancing  the  spark;  when 
we  rotate  the  timer  body  in  the  same  direction 
as  the  camshaft  rotates,  the  spark  will  occur  later 
and  we  call  this  retarding  the  spark.  The  arc 
through  whiclrthe  timer  can  be  rotated  is  slight, 
only  about  10  to  12  degrees,  which  corresponds 
to  20  to  24  degrees  of  crankshaft  movement; 
this  is  because  that  much  advance  is  sufficient 
to  accomplish  the  purpose  at  the  highest  speeds 
and  further  advance  is  harmful  to  the  engine;  it 


DISTRIBUTOR  GEAR  MAGNETS  HIGH  TENSION  COIL 

-^^^^^^^^^^  CONDENSER 

HIGH  TENSION  BRUSH 

OIL  RESERVOIR       • 

COLLECTOR  RINC 


BREAKER  POINTS 
LOCK  NUT 


GROUND  BRUSH 
CAM 


UPULSE  STARTER 


ADVANCE  LEVER       '  '  *HB  "          CATCH' 

ARMATURE  GEAR      /     <7,        •  COLLECTOR  BRUSH 

PRIMARY  WINDING          ARMATURE 


Fig.   126.     Magneto  and  impulse  starter. 

likewise  is  not  advisable  to  retard  the'  spark 
further  than  is  allowed  for  by  this  limited  arc. 

The  second  method  of  increasing  the  electrical 
pressure  to  a  point  where  it  will  jump  the  plug 
gap  is  based  upon  exactly  the  -  same  principles 
as  outlined  above;  but  the  entire  apparatus,  in- 
stead of  being  made  up  in  the  form  of  separate 
units,  is  included  in  a  single  instrument  which 
is  called  a  magneto  (Figure  126). 

The  device  comprises  a  set  of  strong  electro- 


210 


Tractor  Engines. 


Fig.  127.     Testing  magnets  of  a  magneto. 


magnets,  the  bars  being  horseshoe-shaped  and 
made  of  special  steel,  rich  in  magnetic  proper- 
ties, so  as  to  obtain  the  maximum  effect  (Figure 
127).  Arranged  to  rotate  in  the  magnetic  field 

set  up  by  these 
magnets  in  a 
m  a  n  n  e  r  t  o 
take  da  van- 
tage of  the 
greatest  num- 
ber of  lines 
of  force,  is  an 
armature 
made  of  soft 
iron.  Wound  on  this  armature  is  a  coil  compris- 
ing a  comparatively  large  number  of  turns  of 
fairly  heavy  wire.  One  end  of  this  coil  is 
"grounded"  to  the  armature  itself  and  the  other 
end  is  brought  out  to  a  screw  on  the  end  of  the 
armature  shaft  by  means  of  which  it  is  carried 
to  a  circuit  breaker.  The  arrangement  is  such 
that  the  contact  of  the  circuit  breaker  touches 
grounded  contact  located  on  the  breaker  disc,  so 
that  ordinarily  the  circuit  is  complete,  an$ 
when  the  armature  is  rotated  the  current  gen- 
erated in  the  coil  flows  to  ground  through  the 
circuit  break- 
er and  thence 
back  to  the 
grounded  ter- 
minal of  the 
coil.  But  twice 
during  each 
revolution  of, 
the  armature 
shaft  a.  little 
cam  (Figure 

128)     On     the  Fig    128.     Magneto   breaker  points. 


Ignition  System.  211 

breaker  housing  is  brought  into  contact  with  the 
lever  of  the  circuit  breaker,  lifting  it  from  contact 
with  the  grounded  contact,  and  thereby  inter- 
rupting the  circuit  exactly  as  was  done  with  the 
electro-magnetic  circuit  breaker  described  in  con- 
junction with  the  induction  coil.  The  only  dif- 
ference is  that  there  is  but  a  single  break  in  the 
case  of  the  magneto.  A  condenser  is  shunted 
across  the  breaker  points  exactly  the  same  as 
with  the  coil  and  it  serves  the  same  purpose ; 
it  checks  the  flow  of  current  immediately  and 
stops  arcing  at  the  breaker  points. 

From  what  we  know  of  the  performance  of 
the  current,  it  is  not  hard  to  see  that  all  around 
the  coil  on  the  armature,  we  are  going  to  have  set 
up  a  second  magnetic  field  during  the  interval 
when  the  breaker  points  are  closed  and  the  cur- 
rent is  flowing  through  the  coil,  because  the  coil 
itself  is  cutting  lines  of  force.  Nor  is  it  hard  to 
see  that  interruption  of  the  current  flow  by  break- 
ing the  points  apart  with  the  cam  action  is  going 
to  result  in  a  sudden  collapse  of  this  second 
magnetic  field  twice  during  each  revolution  of 
the  magneto  armature. 

This  coil  on  the  armature,  therefore,  correT 
sponds  exactly  to  our  primary  coil  in  the  case 
of  the  induction  coil,  and  we  call  it  the  primary 
coil  of  the  magneto.  Over  it  we  wind  a  sec- 
ondary coil  comprising  a  very  large  number  of 
turns  of  very  fine  wire ;  one  end  of  the  secondary 
we  ground  to  the  armature,  the  connections  cor- 
responding exactly  to  the  coil  connections,  and 
the  other  we  take  to  a  rotary  arm  on  a  distrib- 
utor (Figure  129)  which  is  built  right  in  with 
the  magneto.  This  rotary  arm  turns  as  the  ar- 
mature rotates,  the  gearing  depending  on  the 
number  of  cylinders  on  the  engine,  and  the 
arrangement  is  such  that  each  time  the  breaker 


212 


Tractor  Engines. 


points  open, 
the  arm  is  in 
contact  with 
a  segment  on 
the  distributor 
plate  so  that 
the  high  -  ten- 
sion current  is 
directed  to  the 
cylinder  plug 
in  the  cylin- 
der ready  to 
fire.  Each 
segment  has  a  cable  leading  to  a  plug,  and  the 
connections  are  made  in  accordance  with  the 
firing  order  of  the  engine  (Figure  130). 

In  order  to  advance  and  retard  the  spark,  as 
we  did  in  the  case  of  the  coil  ignition  system,  we 
rotate  the  breaker  box  slightly;  rotation  in  the 
direction  opposite  to  the  rotation  of  the  arma- 


129.      Distributor  construction. 


.  /so 


Fig.    130.     How  magneto   is  wired   in   accordance  with  engine 
firing  order. 


Ignition  System.  213 

ture  results  in  earlier  opening  of  the  breaker 
points  and  advance  in  the  time  of  sparking; 
rotation  in  the  same  direction  as  the  armature 
retards  the  spark. 

In  the  case  of  slow-running  engines,  where 
we  cannot  turn  them  over  fast  enough  to  assure 
rapid  movement  of  the  armature  and  the  pro- 
duction of  a  good  hot  spark,  the  armature  is 
fitted  with  a  special  coupling  through  which  it 
is  driven  and  which  we  call  an  impulse  starter. 
It  is  simply  a  little  device  which  stops  rotation 
of  the  armature  at  some  point  in  its  revolution 
and  holds  it  until  the  piston  is  in  proper  position 
for  the  spark  to  pass,  the  meantime  winding  up 
a  spring.  Immediately  the  proper  piston  position 
is  attained,  a  trip  releases  the  armature  and  the 
spring  gives  it  a  very  quick  turn  over  the  point 
where  the  breaker  opens,  and  we  have  a  good, 
hot  spark  for  starting. 

There  is  one  other  system  of  ignition  used  on 
a  few  tractors  which  is  interesting,  although  not 
frequently  met  with  at  the  present  time.  This 
we  call  low  tension  or  "make-and-break"  igni- 
tion, for  the  reason  that  the  •  current  is  not 
stepped  up  to  a  point  where  it  will  jump  a  gap 
in  the  cylinder.  In  fact,  in  the  cylinder,  ,the 
sparking  points  are  brought  together  just  before 
the  spark  is  desired  and  the  current  flow  is  estab- 
lished, and  then  very  quickly  separated  at  the 
instant  the  spark  is  required,  with  the  result  that 
in  separating,  due  to  the  inertia  of  the  current 
as  described  above,  the  current  tends  to  jump 
the  widening  gap  and  we  obtain  a  spark.  Natu- 
rally, since  a  spark  across  these  contacts  is  just 
what  we  want,  no  condenser  is  used  with  this 
system. 

The  mechanical  arrangement  of  the  system 
as  applied  to  the  Rumely  tractor  is  made  per- 


214 


Tractor  Engines. 


fectly  plain  in  Figure 
131.  A  cam  actuates  a 
rod  whereby  the  points 
are  first  brought  to- 
gether in  the  cylinder 
and  then  very  rapidly 
separated  when  the 
rod  tappet  drops  off 
the  hill  of  the  cam  at 
the  instant  the  spark 
is  wanted.  The  elec- 
trical circuit  is  very 
simple;  either  a  low- 
tension  magneto  is 
used  and  connected 
directly  to  the  insu- 
lated spark  plug  termi- 
nal, the  other  side  be- 
ing grounded,  or  else  a 
set  of  dry  cells  is  em- 
ployed, in  which  case 
the  voltage  is  in- 
creased slightly  by 
running  the  current 
through  an  induct- 
ance coil,  which  is  a 
single  coil  of  very  heavy  wire  wound  over  a 
soft  iron  core.  The  inductive  effect  of  the  field 
set  up  by  this  coil  on  the  coils  themselves  gives 
rise  to  'self-induction/'  whereby  the  higher  volt- 
age necessary  to  produce  an  effective  spark  is 
obtained. 


Fig.     131.       Low     tension 
niter  on  Rumely  tractor. 


CHAPTER  X. 


Care  of  Ignition  System. 

THE  high-tension  magneto  is  one  which  fur- 
nishes a  jump  spark  without  the  use  of  a 
spark  coil.  In  a  magneto  of  this  kind,  the  arma- 
ture, in  addition  to  serving  the  purpose  of  an 
ordinary  armature,  also  acts  as  a  coil,  or  step- 
up  transformer,  and  with  its  interrupter  and 
distributor  forms  a  complete  ignition  system,  the 
only  outside  parts  being  the  spark  plugs. 

On  account  of  the  K.  W.  Magneto  being  of 
this  •  compact  type,  eliminating  coils,  batteries, 
extra  wiring  and  trouble  of  shortage,  it  was 
chosen  as  part  of  the  equipment  of  the  "Twin 
City"  motors. 

K.  W.  Magneto,  Model  HK.  By  oscillating 
the  breaker  box,  as  shown  in  Figure  132,  the 

spark  is  advanced  or 
retarded.  Full  retard 
is  when  the  spring  is 
almost  touching  the 
spider  marked  E. 
When  this  spring 
touches  the  spider, 
the  circuit  is  ground- 
ed, and  this  stops  the 
motor.  It  is  well  for 
the  operator  to  re- 
move the  circuit 
breaker  once  a  week 
or  more  and  clean  out 
any  surplus  oil,  then 
oil  the  wick  in  the 


Fig.  132.     K-W  magneto. 


(215) 


216 


Tractor  Engines. 


IOO 


roller  on  the  upper  contact  arm  with  two  or  three 
drops  of  good  sewing  machine  oil.  Make  sure 
that  the  contact  points  are  clean,  and  that  no 

oil    has    lodged 
on  them. 

Oil  on  the 
breaker  paints 
is  an  insula- 
tion, and  will 
c  a  u  s  e  Si  ar  d 
starting  a  n  d 
probable  miss- 
in  g  at  I  o  w 
speed.  In  re- 
placing the  cir- 
c  u  i  t  breaker 


Fig.    133.     Cross-section 
magneto,  model  H-K. 


K-W 


box,  be  sure 
that  the  contact 
spring  No.  189  has  been  properly  replaced,  and 
that  nut  No.  79  is  tight  (Figure  133). 

Once  a  week  place  a  few  drops  of  oil  in  each 
of  the  three  bearings.  One  oiler  is  located  on 
each  side  of  the  rotor  shaft  and  one  bearing  on 
the  distributor  shaft. 

At  least  once  a  week  look  at  the  distributor 
and  see  that  it  is  free 
from  carbon  dust.  This 
is  accomplished  by  re- 
moving the  high-ten- 
sion cable  marked  100 
and  the  spider  marked 
No.  1. 

K.  W .  Magneto, 
Model  TK.  To  set 
the  Model  TK  is 
much  the  same  as  the 
HK.  It  is  not  neces- 
sary to  remove  the 


Fig. 
K-W 


134.     Impulse  starter  on 
magneto. 


Care  of  Ignition  System.         217 


Fig.   135.     Testing  magneto. 


distributor  cover,  as  a  sight  glass  is  provided 
at  "A"  through  which  a  small  hole  locates 
the  position  of  the  distributor  brush. 

The  motor 
is  stopped 
when  pro- 
jector  "D" 
touches  screw 
"E." 

The  break- 
er box  is  the 
same. 

To  time 
the  magneto. 
1.  Have  pis- 
ton in  cylin- 
der No.  1  at  highest  point  of  compression,  which 
is  firing  position.  Have  rocker  arm  "A"  (Figures 
137-138)  horizontal  as  shown.  2.  Shift  magneto 
around  until  distributor  brush-  "B"  touches  seg- 
ment "S,"  thus  connecting  with  cylinder  No.  1. 
3.  Shift  magneto  slowly  by  hand  to  the  right 
until  contacts  "P"  are  just  beginning  to  separate. 
This  is  the 
firing  point  of 
the  magneto, 
and  must  oc- 
cur when  the 
piston  is  at 
highest  point 
of  firing 
stroke.  It 
will  be  found 
that  the  mag- 
n  e  t  o  will 
have  to  be 

advanced  slightly  from  this  setting  on  account 
of  the  impulse  starter.  Rotate  the  magneto  to 


Fig.    136.     Filing   breaker   points. 


218 


Tractor  Engines. 


the  right  several  holes.  The  impulse  starter 
should  trip  just  as  the  top  center  mark  on  fly- 
wheel passes  center  point  on  engine  for  about 
one  inch.  At  this  point  secure  magneto  with  the 
two  bolts  through  the  coupling  flange. 


P'jrriHG/    ORDER  J-3-4-2 
FOUR  CYLINDERS 


MAGNETO 

Fig.    137.     Timing  K-W  magneto  to  a  four-cylfnder  engine. 


Six    CVLIMDERS 
FIG.  139 


Fig.    138.     Timing   K-W   magneto   to   a   six-cylinder   engine. 

4.  When  one  cylinder  is  all  right,  proceed  to 
connect  the  others,  as  shown  in  the  diagram. 
The  firing  order  is  1,  3,  4,  2  on  the  four-cylinder 
motors,  and  1,  4,  2,  6,  3,  5  on  the  six-cylinder 
motors. 


Care  of  Ignition  System.         219 

5.  Replace  parts  on  the  magneto  and  start  the 
engine  to  test  the  setting.  See  that  all  nuts  and 
connections  are  tight,  especially  nuts  55  and  56, 
Figure  133.  Also  see  that  retainer  spring  No. 
189  has  been  replaced.  To  advance  shift  coup- 
ling against  direction  of  rotation.  To  retard  shift 
coupling  with  direction  of  rotation. 

Finding  which  cylinder  misses.  Open  priming 
cups  one  at  a  time.  Watch  for  the  flame  shoot- 
ing out,  and  listen  for  the  sharp  report.  The 
cylinder  that  only  hisses  and  makes  no  report  is 
the  one  at  fault.  The  missing  might  be  from 
the  following  causes : 

1.  Too  much  water  when  running  on  kerosene. 

2.  Too  much  fuel. 

3.  Crack  in  porcelain  of  spark  plug. 

4.  Poor  porcelain  in  spark  plug. 

5.  Spark  plug  gap  out  of  adjustment. 

6.  Valve  or  tappet  sticking. 

7.  Wire  leakage. 

8.  Magneto  trouble. 

(1)  Usually   when   the   cylinder   stops   firing 
from   the   first   cause,   a   white   smoke   emerges 
from  the  priming  cup,  and  by  closing  the  water 
valve  and  changing  to  gasoline  the  trouble  can 
be  remedied. 

(2)  Adjustment  of  the  fuel  valve  and  allow- 
ing more  air  will  remedy  this. 

(3)  and   (4)    Change  spark  plugs  by  placing 
the  supposedly  defective  one  in  a  cylinder  that 
is  firing. 

(5)  Gap  should  be  about  1-32". 

(6)  Remove  the  valve  or  tappet  and  with  a 
fine    emery    cloth    smooth   the    surface    and    oil 
well  before  replacing. 


220 


Tractor  Engines. 


(7)  Remove  the  wire  and  hold  about 
from  the  cylinder  (Figure  139).  If  there  is 
no  spark,  remove  the  wire  from  its  fastenings, 
but  first  test  out  the  magneto  by  placing  a  wire 


Fig.   139.     Detailed  method  of  testing  spark  plug. 

in  the  defective  wire  connection  on  magneto  and 
hold  close  to  some  part  of  the  motor.  If  this 
shows  a  spark,  then  there  must  be  a  breakage 
in  the  insulation  around  the  wire. 

(8)     There  are  two  places  where  the  trouble 


Care  of  Ignition  System.         221 

may  be  remedied.  One  is  the  breaker  box  and 
the  other  the  distributor.  If  these  two  places 
are  well  cleaned,  and  the  trouble  has  not  been 
located,  there  might  be  dirt  lodged  in  between 
the  magnets.  Clean  this  out  thoroughly,  and  if 
this  does  not  remedy  the  trouble,  the  magneto 
should  be  removed  and  shipped  back  to  the  fac- 
tory. It  is  well  for  the  operator  to  have  an  extra 
breaker  box.  In  this  way  he  would  eliminate  a 


TO  TEST  SPARK.     (See  Fig.  139.) 

Remove  high  tension  wire  from  spark  plug.  Hold  it  one- 
fourth  of  an  inch  away  from  the  plug.  When  the  engine  is 
turned  over  with  the  switch  turned  onto  the  batteries  there 
should  be  a  spark.  If  not,  test  the  batteries. 

Do  not  under  any  circumstances  when  testing  spark 
allow  the  end  of  the  clip  on  the  high  tension  wires  to  be 
more  than  %  of  an  inch  from  some  metal  as  when  you  do 
and  the  motor  is  running  there  is  a  re-action  sets  in  which 
is  extremely  hard  on  the  coil. 

If  there  is  a  spark,  remove  the  spark  plug.  Attach  the 
wire  the  same  as  though  the  plug  was  in  place.  Lay  it  on 
the  cylinder.  (See  cut.)  If  there  was  a  spark  when  the 
first  test  was  made  there  should  be  one  now.  (Have  spark 
plug  gap  set  as  per  instructions  under  spark  plugs.)  If  no 
spark  appears  at  the  gap,  the  chances  are  that  there  is  a 
broken  porcelain. 

CAUTION — At  no  time  should  the  wires  touch  the 
cylinders  nor  be  allowed  to  get  water  soaked,  as  this  will 
cause  a  short  circuit.  If  a  spark  appears  at  the  gap  and 
the  cylinder  does  not  fire  it  is  reasonable  to  assume  that  the 
cylinder  has,  (a)  too  much  lubricating  oil  in  the  combustion 
chamber,  (b)  is  wet  or  (c)  does  not  get  the  proper  mixture 
of  gas,  (d)  engine  has  lost  compression. 


lot  of  lost  time  in  testing  this  part  of  the  mag- 
neto out  by  simply  removing  the  old  one  and 
slipping  the  extra  one  on. 

Spark  Plugs. — The  spark  plugs,  perhaps,  will 
require  more  attention  than  any  other  part  of 
the  ignition  system.  They  will  require  cleaning 
from  time  to  time,  because  carbon  is  bound  to 
form  in  any  engine  burning  a  hydrocarbon  as 
fuel,  and  is  bound  to  be  troublesome  in  a  case 
where  the  engine  is  over-oiled  or  where  the  car- 


222  Tractor  Engines. 

buretor  is  adjusted  to  supply  too  rich  a  mixture. 
This  carbon  will  deposit  on  the  inside  of  the 
shell  covering  the  insulator,  and  since  carbon  is 
a  good  conductor  of  electrical  current,  will,  in 
time,  present  an  easier  path  for  the  flow  of  the 
current  than  the  plug  gap,  and  missing  will  be 
the  result. 

To  test  for  a  short-circuited  plug,  have  the 
engine  running  at  the  speed  at  which  the  miss 
is  most  noticeable.  Take  a  wooden-handled 
screwdriver  and  touch  the  blade  to  the 'terminal 
of  the  first  plug  and  to  the  metal  of  the  engine 
at  the  same  time.  This  will  short-circuit  it  and 
there  will  be  no  spark.  If  this  plug  has  been 
missing,  this  will  have  no  effect  on  the  opera- 
tion of  the  engine ;  if,  however,  this  happens  to 
be  a  good  cylinder,  the  miss  will  be  emphasized. 
Do  this  with  all  the  cylinders  in  turn  until  the 
one  is  located  where  the  short-circuiting  has  no 
effect  on  the  operation.  Remove  this  plug  and 
replace  it  with  another  known  to  be  in  good  con- 
dition and  the  trouble  will  disappear. 

If  a  plug  is  badly  short-circuited,  it  can  be 
tested  by  laying  it  on  the  cylinder  with  the  plug 
cable  attached  and  seeing  if  a  spark  jumps  the 
gap.  If  it  does,  the  plug  is  O.  K.  If  not,  it  needs 
attention.  This  test  is  not  conclusive,  however, 
because  it  is  a  well-known  fact  that  the  spark 
will  jump  the  gap  easier  in  the  open  air  than 
under  the  conditions  encountered  in  the  cylinder ; 
it  may  show  a  spark  on  the  outside  and  still  fail 
to  function  in  the  engine,  which  causes  quite  a 
bit  of  annoyance  to  the  inexperienced  operator. 

One  of  the  larger  spark  plug  makers  has 
brought  out  a  little  spark  plug  cleaner  which 
should  be  in  every  tool  kit.  It  is  a  small  glass 
jar  shaped  like  a  chemist's  test  tube,  flared  at 


Care  of  Ignition  System.         223 


the  open  end,  where  a  rubber  collar  is  fitted 
of  a  size  adapted  to  fit  the  shell  screw  of  the 
plug.  In  the  jar  are  a  couple  of  dozen  steel 
needles.  The  plug  is  screwed  into  this  jar,  which 
should  be  half  filled  with  gasoline,  and  violently 
agitated  for  a  few  mo- 
ments. The  combined 
action  of  the  gasoline 
and  the  pricking  action 
of  the  needles  which 
come  in  contact  with  the 
entire  surface  of  the  in- 

Fig.    140.     Spark  plug  gaps.      sujatorj    act    tQ    dean    the 

carbon  off  in  a  jiffy,  leaving  the  plug  perfectly 
clean. 

In  the  absence  of  such  a  device,  unscrew 
the  compression  nut  and  remove  the  porcelain  or 
mica  insulator.  Clean  the  carbon  off  with  fine 
sandpaper  or  emery  cloth ;  clean  inside  of  the 
shell.  It  is  a  good  plan  to  examine  the  porcelain 
insulator  for  cracks,  discarding  it  if  it  shows  any, 
and  replacing  the  old  one  with  a  new  insulator, 
which  the  maker  is  prepared  to  supply.  It  is  well 
also  to  put  in  new  compression  washers  when 
cleaning  the  plugs,  as  the  old  ones  lose  their 
life.  S  e  t  up 
the  compres- 
sion nut  firm- 
ly to  prevent 
leakage.  Al- 
w  a  y  s  adjust 
the  plug  gap 
(Figures  140 
and  141)  to 
.025  or  .030 
of  an  inch  and  adjust  all  the  plugs  the  same.  It  is 
well  to  use  one  make  of  plug  throughout  the  cylin- 
ders; it  makes  replacement  and  handling  easier. 


141 


Fig.  141.  Method  of  ascertaining  correct 
adjustment  of  plug  gap  with  a  "feeler" 
gauge. 


224  Tractor  Engines. 

Ignition  Coils. — The  ignition  coils  as  used  are 
perfectly  adjusted  at  the  factory,  and  this  ad- 
justment should  not  be  disturbed  except  to  install 
new  contact  points  or  to  reduce  the  gap  between 
the  points,  which  naturally  will  increase  with 
wear. 

If  the  contact  points  are  found  to  be  burned 
or  pitted,  they  should  be  filed  flat  with  a  mag- 
neto file  and  then  the  adjusting  thumbnut  should 
be  turned  down  so  that  with  the  vibrator  spring 
held  down,  the  gap  between  the  points  will  be 
a  trifle  less  than  1/32  of  an  inch.  Then  set  the 
lock  nut  so  that  this  adjustment  cannot  be  dis- 
turbed. Do  not  bend  or  hammer  on  the  vibra- 
tors, as  this  will  most  certainly  affect  the  opera- 
tion of  the  cushion  spring  of  the  vibrator  bridge 
and  reduce  the  efficiency  of  the  unit. 

With  the  vibrators  properly  set,  if  any  par- 
ticular cylinder  fails  or  seems  to  develop  weak 
action,  change  the  position  of  the  unit  supplying 
the  spark  to  this  cylinder,  substituting  one  of 
the  other  units  for  it.  If  the  unit  is  really  at 
fault,  the  cylinder  which  operated  badly  before 
will  now  function  properly,  but  the  one  with  the 
bad  unit  will  show  poor  operation.  The  first 
symptom  of  a  defective  coil  unit  is  the  buzzing 
of  the  vibrator  with  no  spark  at  the  plug 
(Figure  142). 

Remember  that  a  loose  wire  connection,  faulty 
spark  plug,  damp  ignition  cable  or  a  faulty  timer 
may  cause  irregularity  in  the  running  of  the 
engine.  These  are  points  that  must  be  considered 
before  laying  the  blame  on  the  coil. 

When  the  vibrators  on  the  coils  are  not  prop- 
erly adjusted,  more  current  is  required  to  make 
and  break  the  contact  between  the  points,  and  as 
a  result,  when  the  engine  is  turned  slowly  by 
hand  to  start,  there  will  not  be  sufficient  current 


Care  of  Ignition  System.         225 

generated  by  the  magneto  to  operate  the  vibrators 
and  hard  starting  will  ensue.  Do  not  allow  the 
contact  points  to  become  ragged.  If  they  are  in 
poor  shape  they  are  very  likely  to  stick  and  cause 


TESTING  COIL. 

Attach  wires  to  four  good  strong  dry  cells  as  shown 
in  cut. 

Wind  the  red  and  yellow  wires  together,  making  one  wire 
out  of  the  two. 

Hold  the  two  high  tension  cables  J4  of  an  inch  apart. 

Throw  switch  on  to  batteries. 

Strike  the  green  wire  smartly  against  the  united  red  and 
yellow  wire. 

If  the  coil  is  good,  there  will  be  a  strong  spark  jump  the 
gap  between  the  two  high  tension  cables. 

CAUTION — Do  not  mistake  a  damp  coil  for  a  defective 
one.  Do  not  mistake  a  set  of  poorly  insulated  wires  which 
are  shorting  for  a  defective  coil.- 

NEVER  USE  MORE  THAN  SIX  DRY  CELLS. 

NOTE — In  case  your  coil  gets  wet  or  if  you  are  having 
trouble  and  think  it  is  in  the  coil,  do  not  write  the  factory 
or  send  for  an  expert,  but  take  the  coil  off,  put  it  in  a 
WARM  oven  and  thoroughly  dry  it  out. 

Now,  test  your  coil  as  instructed,  connected  to  good  dry 
cells  and  if  it  then  refuses  to  work,  it  is  time  to  call  for 
help. 

'Be  sure  that  it  is  properly  wired,  as  per  the  wiring  in- 
structions pertaining  to  this  particular  magneto. 


Fig.  142.     Detailed  method  of  testing  ignition  coil. 


226  Tractor  Engines. 

unnecessary  difficulty  in  starting  and  are  apt  to 
cause  an  occasional  miss  when  the  engine  is 
running. 

In  order  to  determine  which  cylinder  is  miss- 
ing without  resorting  to  the  use  of  a  screwdriver 
to  short-circuit  the  plugs  open  the  throttle  until 
the  engine  is  running  at  a  fairly  lively  clip  and 
then  hold  down  the  vibrators  on  the  two  outside 
coils.  Do  this  with  the  fingers  just  preventing 
the  vibrators  from  buzzing.  This  will  stop  two 
cylinders  from  firing.  If  the  remaining  two  fire 
regularly  it  is  evident  that  they  are  not  at  fault 
and  that  the  miss  must  have  come  from  one  or 
the  other  of  the  cylinders  you  have  put  out  of 
commission.  Now  relieve  No.  4  and  hold  down 
the  other  three;  if  the  engine  continues  to  run, 
the  trouble  will  be  with  No.  1.  In  this  manner, 
all  the  cylinders  can  be  tested  in  turn  and  the 
missing  one  located.  Do  not  forget  that  Coil  4 
leads  to  Cylinder  3  and  Coil  3  to  Cylinder  4. 
When  the  missing  cylinder  has  been  located,  ex- 
amine both  spark  plug  and  vibrator  as  well  as 
the  wiring. 

Commutator  or  Timer.  —  The  commutator 
should  be  kept  clean  and  well  oiled  with  light 
machine  oil  at  all  times.  If  ignition  trouble  is 
experienced  which  cannot  be  traced  to  the  plugs 
or  the  coils,  examine  first  the  wiring  leading  to 
the  commutator.  In  case  this  is  chafed  and  is 
making  contact  with  some  metal  part  of  the  trac- 
tor, the  primary  circuit  will  be  short-circuited  and 
we  will  have  a  continual  buzz  of  one  or  more  of 
the  vibrators ;  sometimes  the  contact  will  be  made 
intermittently,  with  the  result  that  the  cylinder 
affected  will  fire  at  the  wrong  time.  This  is  a 
dangerous  condition,  and  it  is  highly  advisable 
when  this  wiring  shows  wear,  to  discard  it,  and 
put  in  all  new  wire,  being  careful  to  follow  care- 


Care  of  Ignition  System.         227 

fully  the  wiring  arrangement  between  the  coils 
and  the  commutator.  If  one  cylinder  persists  in 
missing,  and  there  is  no  buzzing  of  the  vibrator 
on  that  particular  cylinder,  it  is  evident  that  the 
commutator  brush  is  not  making  contact  on  that 
particular  segment,  or  else  the  wire  to  that  coil 
from  the  commutator  is  broken  inside  the  insu- 
lation. Test  for  the  latter  by  removing  the  wire 
from  the  commutator  terminal  and  touching  to 
any  metal  part  of  the  car.  If  the  vibrator  buzzes, 
the  trouble  is  in  the  commutator;  if  there  is  no 
buzz,  the  wire  is  probably  broken  and  should  be 
replaced  with  a  new  one. 

If  misfiring  occurs  when  running  at  high  speed, 
inspect  the  commutator.  The  surface  of  the  ring 
around  which  the  roller  travels  should  be  clean 
and  smooth,  so  that  the  roller  makes  a  perfect 
contact  at  all  points.  If  the  roller  fails  to  make 
a  good  contact  on  any  one  of  the  four  segments, 
the  corresponding  cylinder  will  not  fire.  Clean 
these  surfaces  if  dirty.  In  case  the  fiber,  seg- 
ments and  roller  are  badly  worn,  the  most  satis- 
factory remedy  is  to  replace  them  with  new 
parts.  The  spring  should  be  strong  enough  to 
ensure  a  good,  firm  contact  between  the  roller 
and  the  segments. 


CHAPTER  XI. 


Engine   Troubles. 
TKeir  Causes  and  Remedies. 

THE  following  suggestions  may  be  of  assist- 
ance in^  locating  and  remedying  engine 
troubles.  These  suggestions  are  made  to  enable 
the  operator  to  effect  emergency  repairs  in  the 
field.  In  all  but  the  simplest  cases  we  recom- 
mend that  the  trouble  .be  submitted  to  a  compe- 
tent repairrrian  for  correction. 

The  points  under  the  following  subheadings 
have  been  arranged,  in  so  far  as  possible,  in 
related  groups. 

For  example,  under  the  subheading  "Engine 
Refuses  to  Start,"  points  2  to  4,  inclusive,  deal 
with  Ignition;  points  7  and  8  with  Compression, 
and  points  5  and  9  with  Fuel. 

It  is  recommended,  in  every  case  of  trouble, 
that  the  operator  look  for  the  simplest  cases  and 
apply  the  simplest  remedies  first,  working  up 
progressively  through  the  more  complex. 

ENGINE  REFUSES  TO  START. 


CAUSES    OF    TROUBLE. 

1.  Ignition  switch  off. 

2.  Broken    electrical 
circuit. 


3.     Interrupted    electri- 
cal circuit. 


4.  Fouled     or     broken 
spark  plug. 

5.  Insufficient  ga-soline 
supply.    t 

6.  Poor  carburetion. 


REMEDIES. 

1.  Turn  switch  to  starting  position. 

2.  Examine  wiring  for  break.     See 
.  that     connections     at     mganeto     and 

spark    plug   terminals    are    clean    and 
tight. 

3.  Lack    of   insulation    may   cause 
a    ground   connection    or    a    short-cir- 
cuit.     Rewind  defective  wiring  with 
tape   or  renew  wiring. 

4.  Clean  foul  plug;  replace  cracked 
plug. 

5.  Test    for    gasoline    sup'ply     at 
carburetor    by     flooding.       Replenish 
supply   in   gasoline  tank. 

6.  Mixture   too   lean    or  too    rich. 
Adjust  carburetor  for  correct  mixture. 

(228) 


Engine  Troubles. 


229 


CAUSES    OF    TROUBLE. 

r.      Poor  compression. 


REMEDIES. 

7.  Test  compression  by  hand- 
cranking. 

(a)  The  piston  rings  may  be 
gummed  or  stuck  in  their  recesses. 
After  a  run,  while  the  engine  is  still 
warm,  introduce  about  two  table- 
spoonfuls  of  kerosene  through  the 
priming  cocks  of  each  cylinder  and 
allow  it  to  remain  over  night.  This 
will  free  the  rings. 


A — Open  the  pet  cock  in  the  end  of  the  cylinder  and  blow  out 
any  oil  by  turning  the  engine  over. 


B — Look  for  a  leaky  intake  manifold  gasket. 
Fig.  143.     Tracing  troubles. 


232 


Tractor  Engines. 


CAUSES    OF    TROUBLE. 


13.     Worn     or 
piston  rings. 


broken 


REMEDIES. 

line  is  indicated.  Further,  the  jet 
of  carburetor  may  be  clogged,  in 
which  case  remove  and  clean  jet. 

13.  Renew  worn  or  broken  rings. 
Use  correct  oil — an  oil  which  wi" 
form  a  perfect  piston  ring  seal. 


ENGINE  MISFIRING. 


1.     Carbon     on     spark 
plugs. 


2.     Insufficient     g  a  s  o- 
line  supply. 


3.  Fuel     mixture     too 
"lean." 

4.  Fuel     mixture     too 
"rich." 

5.  Valve  stuck. 

6.  Intake    manifold 
leaks. 


1.  Clean  or  replace  plugs.    Select 
correct  oil   to   meet  requirements   of 
engine.      Adjust   carburetor   for   cor- 
rect   mixture. 

2.  Replenish     supply.       See     that 
"shut-off"    cock    in    gasoline    line    is 
wide    open    and    that    there    are    no 
leaks. 

3.  Too  much  air;   too  little  gaso- 
line. 

4.  "Rich"    mixture    will    be    indi- 
cated by  misfiring  in  the  cylinders. 

5.  Clean    valve    stem    with    kero- 
sene. 

6.  Examine     for    air    leaks    and 
repair. 


ENGINE  STOPS. 
Ignition    switch    off.  1.     Turn  switch   on. 


1. 

2.     Broken 
circuit. 


electrical 


3.  Contact     in    jtimer 
poor. 

4.  Insufficient  spark. 


5.     No  gasoline. 


2.  Examine    terminals    for    loose 
connections.       Examine     wiring     for' 
poor  insulation  or  break. 

3.  Clean    and    make    adjustments 
for   strong  contact. 

4.  (a)      Magneto     demagnetized. 
Have  remagnetized.       „ 

(b)  Spark  plug  points  improperly 
adjusted.  Adjust  gap  between  spark 
plug  points  to  a  space  of  about  the 
thickness  of  a  postcard.  Too  wide 
or  too  small  a  gap  will  interfere 
with  proper  ignition. 

5.  Replenish  supply  and  note  that 
carburetor   float  chamber  is  full. 


ENGINE  OVERHEATING. 


1.     Over-retarded  spark. 


2.  Incorrect  timing  of 
valves. 

3.  Throttled  exhaust. 


Clogged  muffler. 
Clogged  radiator. 


1.  After     starting,     spark     should 
be  advanced  as  far  as  possible  at  all 
times   unless   engine   labors. 

2.  The  correction   of  this  trouble 
should    be   left   to  'a   competent   gar- 
ageman.       / 

3.  See  that   exhaust  passages  are 
clean  and  that   exhaust   valves   raise 
sufficiently. 

4.  Disconnect  and  clean  out  soot 
and  products  of  incomplete  combus- 
tion. 

5.  Introduce    cleaning    compound 
into    radiator   and   allow   it   to   circu- 
late while  car  is  running  from  50  to 
100  miles.     Then  wash  out  thoroughly 
with  clean  water.     I^rain  and  refill. 


Engine  Troubles. 


233 


CAUSES    OF    TROUBLE. 

6.  Deficient  water  cir- 
culation. 

7.  Fan  not  working. 

8.  Racing     of     engine 
on  low  gear. 

9.  Continued    use    of 
low  gear. 

10.  Lack  of   oil,   or   in- 
correct   oil. 

11.  Incorrect    carbure- 
tion. 


REMEDIES., 

6.  (a)   Test  for  clogging  of  radi- 
ator or  water  jackets. 

(b)  Test  for  clogging  of  water  hose. 

7.  Lubricate  bearings;  tighten  belt. 

8.  Partially   close   throttle,    there- 
by decreasing  speed  of  engine. 

9.  Use  low.  gear    only  when  nec- 
essary. 

10.  Fill    lubricating    system    with 
correct  grade  of  oil. 

11.  Adjust     carburetor     for    -cor- 
rect mixture. 


ENGINE  KNOCKS. 


1. 

far. 


Spark  advanced  too 


2.     Carbon  deposit. 


3. 


Fuel     mixture 
"rich." 

4.     Loose  bearings. 


. 


8. 


Worn  bearings. 

Loose  flywheel. 
Engine  labors. 
Carburetor     float 


leaking. 


1.  Retard     spark     advance     lever 
on    quadrant    of    steering    wheel    to 
prevent  premature  ignition. 

2.  Results     in     preignition.       Re- 
move accumulated  carbon  from  com- 
bustion chamber  and  make  sure  that 
piston    rings    are    free   in    their   re- 
cesses.    Use  correct   oil. 

3.  Reduce    gasoline    feed    by    ad- 
justing carburetor. 

4.  Have     engine     bearings     fitted 
properly  and  tightened. 

5.  Refit,   or,   if    necessary,   renew 
bearings. 

6.  Make  flywheel  fast  to  shaft. 

7.  Change  to  lower  gear. 

8.  Remove  and  repair  float. 


Over-retarded  spark. 
Insufficient   spark. 


3.     Fuel 
weak. 


mixture     too 


EXPLOSIONS  IN  MUFFLER. 

1.  Advance  spark  for  earlier  ig- 
nition. 

2.  (a)       Magneto    demagnetized. 
Remove  and  have  remagnetized. 

(b)  Spark     plug     defective.       Re- 
new plug. 

(c)  Spark  plug   points  improperly 
adjusted.     Adjust  gap  between  spark 
plug    points    to    a    space    about    the 
thickness  of   a   post-card. 

3.  Too  much  air;   too  little  gaso- 
line.     An    unconsumed    fuel    charge 
is  forced  into  muffler  and  this  charge 
is    fired     by     a    subsequent     charge. 
Adjust    or    clean    carburetor    so   that 
proper    fuel     mixture     for     complete 
combustion  is  admitted  into  combus- 
tion  chamtfer. 

4.  Remove  valve  cap  and  free  valve 
in  guide.    Regrind  valve  if  necessary. 
See  that  spring  has  proper  strength. 

OVERHEATED  EXHAUST  PIPE. 

Over-retarded  spark.  1.  Advance  spark  for  earlier  ig- 

nition. 

Clogged  muffler.  2.  Disconnect  muffler  and  remove 

soot  and  products  of  incomplete 
combustion. 


4.     Exhaust  valve  stuck. 


2. 


APR  12- '84  - 


,,.*« 


477 

Hal lock,  S 


TL233 
H28 


Tractor 


engines. 


PHYSICAL' 
SCIENCES 
LIBRARY 


T-L 1 33 

14 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 


